utility method to find services with a list of tags
leave a sensible comment
add graceful handling of services without tags

Signed-off-by: Craig Furman <cfurman@pivotallabs.com>
rename find all services with all tags method to be less ambiguous

Signed-off-by: Craig Furman <cfurman@pivotallabs.com>
add additional edge-case unit tests for finding all services by all tags

Signed-off-by: Craig Furman <cfurman@pivotallabs.com>
rename method to be more consistent with existing methods

Signed-off-by: Craig Furman <cfurman@pivotallabs.com>
document new find_all_by_all_service_tags in README

Signed-off-by: Craig Furman <cfurman@pivotallabs.com>
Merge pull request #3 from cloudfoundry/find_services_by_many_tags

Find all services that have certain tags