feat(filter/select): Adds a 'select' filter

Adds a 'select' filter to angular-translate. This filter allows user to select some value
based on the value of a given token. This might be useful, for example, to pick gender or
something like that.

Example:

Dear {{ 'she' | select : {he : "Mr.", she : "Mrs.", other : "user"} }} Mary, nice to see
you again!

will become

Dear Mrs. Mary, nice to see you again!