Fixing evaluation of results from lazy to strict.

* Lazy evaluation, the default for Haskell, was causing it to finish the indexing quickly, while not having completely evaluated the indexes. Thus, evaluation was being offloaded for the first time they were used, on the first query. I have changed the ($) use for ($!), in the indexes construction, so as the evaluation is done strict rather than lazy. That way, we can have a better idea of the real time cost of indexing, and should lend itself better for parallelization.

* Small fix on function being used to concatenate filepaths. Using (</>) now, which is portable.
Fixed function used to determine file extension.

* System.FilePath.takeExtension should be more reliable than looking up the end of a String.

* Altered version from 0.0.1 to 0.0.2.