By default in ERP5 all fields are not mandatory

Add transparent SVG and PNG icons to the manifest,
rename all functions following the Nexedi conventions,
link to the TodoMVC homepage, move Handlebars template to head,
and rename all files from tutorial_officejs_* to officejs_todomvc_*.

Fixes failing tests because of always showing "No work to be done" in worklist (lazy bug)

Test Results 20170621-6D7F8E4B

/reviewed-on nexedi/erp5!304

/reviewed-on nexedi/erp5!303

/reviewed-on nexedi/erp5!302

Name is unchanged, but it will use
Products.ERP5Type.Utils.checkPythonSourceCode which uses pylint.

/reviewed-on nexedi/erp5!301

/reviewed-on nexedi/erp5!296

Section bank account item list script was using `parent_strict_group_uid` related key but in 772033ed we removed
`parent_strict_group_uid` related key and added support to generate
`strict_parent_group_uid` related key.

 In that case, *Section Bank Account* field on payment transaction was empty  
![Screenshot_2017-06-16_at_18.54.33](/uploads/4f439bf14fb8b4d54df80031d281ce7a/Screenshot_2017-06-16_at_18.54.33.png) 

The 
`TypeError: Unknown columns ['parent_strict_group_uid']`
was only in the log files, because we are still ignoring errors in TALES.

I'm adding tests to cover this script, it's logic should have been tested anyway.

/reviewed-on nexedi/erp5!295

See discussions in nexedi/erp5!257 from background.

Here we try to reduce the differences in indexation methods that use `DELETE` and then `INSERT` (the one who does not always index the same number of rows).

In `z_catalog_predicate_list` the `DELETE` was missing, so in the case of predicate which stopped being a predicate, that predicate was never removed from the table.


/reviewed-on nexedi/erp5!294

@Tyagov @luke 

/reviewed-on nexedi/erp5!288

( and AccountingTransaction_getDestinationPaymentItemList )

772033ed removed
`parent_strict_group_uid` related key and added support to generate
`strict_parent_group_uid` related key

If rows have been deleted before, it's more natural to simply INSERT and
no need for REPLACE

since predicate is scriptable, a document that was once a predicate may
no longer be a predicate next time it's indexed, so we should remove it
from predicate table in that case.

predicate_category was already doing this correctly

/reviewed-on nexedi/erp5!291

@Tyagov @luke 

During development of JupyterCompile several functions have been used and then removed but their portal_skins remain in ERP5. The purpose of this MR is to remove those skins, since they do nothing. The skins in question are Base_displayHTML, Base_displayImage, Base_saveImage, Base_updateLocalVariableDict and getError.

/reviewed-on nexedi/erp5!289

We pass the `HTTP Exchange` that `inquiry` type based methods can take into account the `HTTP Exchange` that triggered them.

This breaks API, but when discussing with @vpelletier we said that at this stage it's probably OK.

I updated `erp5_payline`, the only usage in this repository.

/cc @gabriel @kazuhiko @aurel @georgios.dagkakis 

/reviewed-on nexedi/erp5!245

@Tyagov @kirr 

When someone imported a module in Jupyter they would get a warning for every module they imported like:

    WARNING: Your imported from the module numpy without...
    WARNING: Your imported from the module datetime without...
    ...

This fix shortens those to just one warning at the end of output like so:

    WARNING: You imported from the modules numpy, datetime, ... without ...



/reviewed-on !278

<dtml-var sql_delimiter> without ;

This caused two problems:
 - If Xfvb was killed and left a stale lock file, we don't reuse this
   display. After some time we end up having "All display locked"
   exception but no Xvfb process running.
 - Xvfb's slapos is patched to store control sockets and lockfiles in
   $TMPDIR ( nexedi/slapos@58462c24 ).
   We don't have $TMPDIR set in testnodes, but this would be a problem
   if we ever set it.

Because Xvfb can detect a stale lock file upon startup and start anyway,
the easy way running Xvfb for each display and see if it's still running
after a few seconds.