[FEATURE] Provide means to create a custom translations file

Add python and config scripts in site/js/build
Include new js script in qgiswebclient.html (commented out)
Include new js script in .gitignore
Adapt documentation
[BUG] Show only available languages in list...

.. of available languages, not all if using custom languages
Add all currently available languages in languages.cfg
Add translators in README source file
Create help_pl.html

Add Polish translations of Help file.
Delete help_pl.html
Create help_pl.html

Add Polish translations of Help file.
Update Translations.js

Added Polish translation of QGIS Web Client in Translation.js
Merge pull request #84 from SaekBinko/master

Polish translation
[BUG?] Zoom to feature selected in searchcombo...

even if reverseAxisOrder is true in WMS for the projection
used. It is not true in the bbox of e.g. PostGIS.
[BUG] show search geometry for searchCombo / wsgi
[BUG] Respond correctly if no geometry is available

if using searchCombo / wsgi
This is true if a search for layers (not their features) is implemented.
fix french translation
Merge pull request #85 from nliaudat/master

fix french translation
added ro to the available help languages
Merge pull request #86 from tudorbarascu/master

added ro to the available help languages
Sample for export functionality
Sample for export functionality
Sample for export functionality
Sample for export functionality
Prevent sql injection