software/theia: add python2.7 in $PATH

so that we can easily use python version 2 or 3 during development and
local testing.

This python is not directly usable with python extension, pip needs to
be installed as user, following:
https://pip.pypa.io/en/stable/installing/#installing-with-get-pip-py

software/theia/software.cfg

@@ -329,7 +329,7 @@ command =
 
 
 [cli-utilities]
-PATH = ${nodejs:location}/bin/:${bash:location}/bin/:${fish-shell:location}/bin/:${tig:location}/bin/:${vim:location}/bin/:${tmux:location}/bin/:${git:location}/bin/:${curl:location}/bin
+PATH = ${nodejs:location}/bin/:${bash:location}/bin/:${fish-shell:location}/bin/:${tig:location}/bin/:${vim:location}/bin/:${tmux:location}/bin/:${git:location}/bin/:${curl:location}/bin:${python2.7:location}/bin/
 
 [theia-wrapper]
 recipe = slapos.recipe.template:jinja2