Add REST API to trigger reindexing

- add parameters to specify path to reindex and toggle recursiveness
- add IndexerGroup.reindex() method to reindex all indexable objects in a repository

Resolves: https://www.pivotaltracker.com/story/show/65168574
Moved credentials into settings.xml file.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	fcrepo-jms-indexer-core/src/main/java/org/fcrepo/indexer/IndexerGroup.java
	fcrepo-jms-indexer-core/src/test/java/org/fcrepo/indexer/IndexerGroupTest.java
	fcrepo-jms-indexer-core/src/test/java/org/fcrepo/indexer/integration/sparql/SparqlIndexerIT.java
Rolled back to httpclient version 4.2.6.