slapos.core == 0.8 fixes critical issue.

Put slapos.libnetworkcache and zc.buildout on slapos.core list.

Recent version of slapos.core is capable to reuse such configuration in order
to run provided buildout with all dependencies.

This is buildout binary with enabled networkcache.

Conflicts:
	software/erp5/software.cfg

Previous version is not available anymore.

0.3.1dev7 refers to non existing file.

Using QGit 2.3 with Git >= 1.7.5 is annoying because it always displays a
warning at startup.

This reverts commit 185ddf09.

This reverts commit 623b55f1.

lxml web site, provided by index, is not functional for long time (weeks).
As it is possible to install it directly form pypi (which has a bit of
mirroring) force such way and do not query source website.

This reverts commit 97268ab6.
kumo : No need to hardcode more.