* adds foundation for bucketStore
* adds prefixedObjStore to buckets package, adjusts gateway-storj accordingly
* fixes multi value assignment problems in gateway-storj
* fixes more multi value assignment errors in gateway-storj
* starts changing miniogw tests to accommodate buckets
* creates bucket store mock
* wip - fixing test cases in object tests
* adds get, put, and list object tests, comments out two test cases
* adds happy scenario tests for bucket methods
* fixes bug in list, removes redundant parts from gateway tests
* fixes nit
* Clean up tests from #188
* Fix bug with timestamp conversion in segment store
* fixes segments.Meta test
* Fix regression in listing objects in a bucket
* adds check to see if bucket is empty before deleting
* updates DeleteBucket test to account for empty/full bucket
* adds TODOs for DeleteBucket and MakeBucket for some cases, adjusts tests, filters out minio errors in logging.go
* adds checks for if buckets already exist or not in DeleteBucket and MakeBucket functions; adjusts tests
* adds BucketNotFound error check in bucket store, removes todo
* adds make_bucket to Travis test, updates boltdb client constructor to always create a bucket (table)
