Merge: Extends catalog with a *try it* and a *download apk* links

Merge: Extends catalog with a *try it* and a *download apk* links

Two new package metadata are added

* `upstream.tryit` for an URL that points to a demo version or a live version of the main web service offered by the package.
* `upstream.apk` for an URL that points to a dry `apk`, or an install page on some store, for the main android application offered by the package.

Moreover, packages that have one them will be respectively tagged `tryit` and `apk`

A demo is available: http://info.uqam.ca/~privat/catalog/#tag_tryit and http://info.uqam.ca/~privat/catalog/#tag_apk

Pull-Request: #1724
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>