More API Functions

[martinszy]

I would like to ask the API:

• The date of the last project in the database
• Order search results (this was discussed in Allow sorting of projects legislative#234 and users should be able to re-order a result list by any field legislative#11)
• The total amount of search results (without actually bringing the query) (this is issue Bill count #51)

[martinszy]

I managed to order the search results in my branch by modifying the search_for method in bills_controller, still not perfect as it sorts by creation_date and not the last date of any paperworks or directives.