-Created SearchFilters class, which we'll use to store and generate the search query strings for the filtered search.
-Changed the way MokapBackend servlet manages the parameters, using the new SearchFilters class
-Merged the searchByString methods in DatastoreAccess class into one, using the SearchFilters class
-Modified MokapSearchController class to fit the new SearchFilters class
-Made the controller variables in MockapBackend servlet local
-Changed the tempFileName generation to improve performance (minor fix)
-Changed visibility of isValidKey in ApiKeyVerifier class to private because it is only used locally
-Fixed some javadoc around the project
Merge branch 'master' of https://github.com/mdebenito/mokap-backend into fiteredsearch

Conflicts:
	MokapBackend/src/main/java/es/eucm/mokap/backend/controller/search/MokapSearchController.java
Solved some merge conflicts
-Fixed small bug that prevented thumbnails to be retrieved in search responses
-Added a searchString field to the response that represents the string used in the query to the database (for debug purposes and highly informative IMO)
-Added toString method to SearchFilters class

Some JDoc pending, the filtered search is working.
Small JDoc addition
Addressed the comments in the PR
Removed unused import
Merge pull request #22 from mdebenito/fiteredsearch

Filtered Search