Implement a repositories combo box dynamic sources

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge remote-tracking branch 'origin/master' into capabilities-stores
Add support for a generated "All repositories" entry (in demand)

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge remote-tracking branch 'origin/master' into capabilities-stores
Add support for excluding repositories with specified facets in repository combo box

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Add support for excluding repositories with specified content classes in repository combo box

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Change capability descriptors to make use of RepositoryCombobox

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge remote-tracking branch 'origin/master' into capabilities-stores
Fix formatting

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Add JavaDoc

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge pull request #138 from sonatype/capabilities-stores

REVIEW: Implement a repositories combo box dynamic source