Add {set,get}_boot_device and get_supported_boot_devices

Add set_boot_device, get_boot_device and get_supported_boot_devices
commands to the client library.

Implements: blueprint new-management-interface
Change-Id: Ib8ba6ef0da9113967f4135dea6e20284eda9d825
Merge "Add {set,get}_boot_device and get_supported_boot_devices"
Updated from global requirements

Change-Id: If908007e999cb3394136d1980267e4cb7c427966
Trim trailing slash and version from endpoint

This commit removes trailing slashes and "/v1" from the endpoint
given when initializing the HTTP client, in order to fix the bug
mentioned below. It also removes the rstrip call in
_make_connection_url, since this is done up front now.

Also adds tests for get_connection_params.

Change-Id: If2c2cd766466dca4621e8daa260575fd4f106f06
Closes-Bug: #1342048
Merge "Trim trailing slash and version from endpoint"
Remove runtime dependency on python pbr
-Prevent pbr handling dependencies