Allow per-repository endpoints
Merge branch 'master' into feature/per-repo-endpoint

Conflicts:
	src/main/java/org/elasticsearch/cloud/aws/AwsS3Service.java
	src/main/java/org/elasticsearch/cloud/aws/InternalAwsS3Service.java
	src/main/java/org/elasticsearch/repositories/s3/S3Repository.java
Allow per-repo protocols

Also add an integration test for custom endpoints/protocols.
Merge branch 'feature/per-repo-endpoint' of https://github.com/brutasse/elasticsearch-cloud-aws into brutasse-feature/per-repo-endpoint
Merge branch 'brutasse-feature/per-repo-endpoint'
Fix unit tests and some bugs introduced by #128

Closes #119, #147