Added specs2.
Added test to see if SlickTagDb correctly creates a database file who's path is passed to its constructor if it doesn't already exist.
Merge branch 'master' into test
Initialize Set to be empty to prevent NPEs.
Added overloaded method.
Added a check for whether or not tags being applied to a file  exist before being applied.
Fixed to reflect recent change to SlickTagDb's API. Removed redundant wildcard.
Added check to see if a tag being added already exists.
Added test suite for SlickTagDb.