#SB-208: Configuration refactoring

- Added GroupResolver* and GroupStorage* classes.
#SB-208: Configuration refactoring

- Introduced support for a configuration basedir (property name: strongbox.basedir).
#SB-208: Configuration refactoring

- Introduced support for a configuration basedir (property name: strongbox.basedir).
#SB-208: Configuration refactoring

- Introduced support for a configuration basedir (property name: strongbox.basedir).
Merge branch 'master' into SB-208
Merge pull request #11 from strongbox/SB-208

SB-208: Configuration refactoring