getDrops: Filter by channel implemented

* List of channel ids can be specified to filter the drop list.
Merge branch 'master' into rivers-dev
Added update SQLs.
getDropsByState Implemented

* Filter drops by read/unread state
getDropsByChannel implemented

* Filter drops by channel name.
getDropsByDate implemented
Added read status to Drop

* Set to true if the authenticated user has marked the drop as read.
searchAccounts Implemented

* Search Account path, name and email using the given query string.
Added avatar to account

* So we do not have to expose email any more.
River Collaborations implemented

* GET,POST,PUT & DELETE methods implemented.
Limit account search results.
Added bucket_name_canonical for buckets
Bucket collaboration implemented.
Added missing rivers table update sql.
Merge branch 'rivers-dev'
Endpoints for adding metadata to bucket drops

* Added endpoints for adding metadata (drops, links, tags, media)
to the drops within a bucket. This was previously being done via
the DropsController; the endpoints (in DropsController) that were being
used for this are no longer available

* Introduced new entities to manage the persistence for the
buckets_droplets table and the associated metadata tables
Merge branch 'master' into buckets-api-dev

Conflicts:
	src/main/java/com/ushahidi/swiftriver/core/api/controller/BucketsController.java
	src/main/java/com/ushahidi/swiftriver/core/api/dao/AccountDao.java
	src/main/java/com/ushahidi/swiftriver/core/api/dao/impl/JpaAccountDao.java
	src/main/java/com/ushahidi/swiftriver/core/api/dao/impl/JpaRiverDao.java
	src/main/java/com/ushahidi/swiftriver/core/api/service/AccountService.java
	src/main/java/com/ushahidi/swiftriver/core/api/service/BucketService.java
	src/main/java/com/ushahidi/swiftriver/core/api/service/RiverService.java
	src/main/webapp/WEB-INF/spring/web-context.xml
	src/test/java/com/ushahidi/swiftriver/core/api/dao/impl/JpaAccountDaoTest.java
	src/test/java/com/ushahidi/swiftriver/core/api/service/AccountServiceTest.java
	src/test/resources/config/sql/test-data.sql