FSBasedStore bug (#139) fix and refactorring
 * refactoring (moving magic strings to constants)
 * broken regexp caused invalid behavior on windows hosts (due to incompatible file separator char) and *-SNAPSHOT versions were not handled correctly - again, the problem was in invalid regexp (regexp was not handling uppercase characters and some other valid characters (like underscore atc.)

fixes #139
Merge remote-tracking branch 'origin/master'