Social, system-wide JavaScript packages and support for uglify-js

[pmetras]

This pull request contains various changes:

• 3 new parameters in myphotoshare.conf to support display options for the social icons. One can select the icons to display with social, if they are coloured or not with social_color and their size with social_size.
• French translation for the new menu options in the top right UI menu.
• Support for new JavaScript minifyier uglify-js which is the default when creating Debian/Ubuntu packages.
• When system-wide JavaScript packages are installed, js-css-minify.sh and index.php will use them instead of the versions provided by MyPhotoShare. This feature can create non reproducible bugs if a user's system has different jQuery versions than the project's ones, but it also gives the user the opportunity to manage updates of jQuery libraries by the security team of the Linux distribution. I've a mixed opinion about this change because ideally, shared JavaScript library should not be included in a project but should be declared mandatory requirements. But as JavaScript does not support modules for traditional web apps, they are distributed in the app. In case of security issue in a library, the whole web app security depend on the author updating regularly the libraries...
• Corrected a bug in index.php where JSON boolean values are understood as string by PHP. Also values are not case sensitive.

[paolobenve]

good work! congratulations!

[paolobenve]

something is wrong, although libjs-jquery package is installed on ubuntu xenial

[paolobenve]

it seems that is because the server must have a /javascript definition, perhaps the docs might say it

[pmetras]

That's strange because when a JavaScript library is installed on Ubuntu/Debian, a virtual directory /javascript is defined on the web server... I don't know how to test for the existence of that virtual directory. I'm testing the presence of the libraries on the file system. Perhaps a test with wget or curl in js-css-minify.css and with PHP functions in index.php? Like I said, I'm not 100% sure this patch is a good idea...