Added transactions.

Summary: Added databases transactions in update a delete method.

Change-Id: I2c6b248c6bdb9f62820a394419b4dd00672080fd
Ability to add queryParameters in URI

Summary: now you can add to uri where parameters. Like:

AppContract.Category.CONTENT_URI.buildUpon()
  .appendQueryParameter(
  	AppContract.Category.PARENT_GUID,
	categoryGuid)
  .build();

Change-Id: I5fbcdff8da9c2e1e296629fb5ab56db00df9a209
Added gradle support

Change-Id: I04d47c4809ba5c75f97c9836a14a899c51ace68f
Fixed limit in content provider

Summary: There were an issue where "limit" was used
as query value when using as queryParameter()

Change-Id: I6584f9b82244dace62eb56a746c35f1b88d4ea8f
Fixed multi parameters query

Summary: now you can use more than one onQueryParameter

Change-Id: If61fde07cea745c01f961308262085fc4e491396