Support Extensions to Trove Client

extensions on the contrib path (i.e. troveclient/v1/contrib/*.py),
extensions on the python path that follow the naming convention of
*_python_troveclient_ext, and entry-points will now be discovered
and loaded.

due to the mismatch of the api version and the troveclient
package name, '1.0' vs. '1', the client has been patched to look
for contrib in troveclient/v1 vs. the standard troveclient/v1_0

Change-Id: I3ea7bb5ba471b0d421581dcfda7216f429cb7b65
Closes-Bug: #1267577
Grants DB access to Users in Instance create API

Reasons:
- When database and users are provided as arguments, created users do not
  get access on suggested databases in cli instance create command.
- This was happening because database was not passed along with user info.

Changes:
- Concatenated the database information with the user info.

Change-Id: I3475f0eab1201b963bb32b2155c175a9483ef92f
Closes-Bug: #1272421
Use Resource() class from common Oslo code

In the process of unification of the clients code we should
reuse common functionality from Oslo. Resource() class from trove
duplicates Oslo funclionality, so we replace it with inheritance

Related to blueprint common-client-library-2

Change-Id: I9809bd3036a5b544b8ff011432f64dc5af793f61
Adding support for incremental backups

* Adds a parent argument to backup-create.
* Adds parent_id to the backup create body if present.

Implements: blueprint incremental-backups

Change-Id: I76f720ae4eadf2a1977c4c2cbf286db4db079b63
Merge "Support Extensions to Trove Client"
Merge "Use Resource() class from common Oslo code"
Merge "Adding support for incremental backups"
Merge "Grants DB access to Users in Instance create API"