Supports bash_completion for ceilometerclient

bash_completion feature can improve CLI user experience, projects like
nova, keystone, and cinder already support it.

NOTE: this patch just provides simple functionality, which means cache
for IDs and names is not used (like nova).

Change-Id: I1b04998a5e7c8818aed4b51f5fe5bf01efd0e14a
Closes-Bug: #1260939
client looking at wrong cacert argument name

fix so client consistently uses 'os_cacert' arg value instead of
either 'os_cacert' or 'cacert'

Change-Id: If5648855aefc7af64178249c270a9ac66907e466
Closes-Bug: #1266472
Python 3: fix test_sample_list

Change the counter_volume field of "fake" samples to get compatibility with
both Python 2 and 3.

In Python 2:

    >>> print(str(0.261666666666667))
    0.261666666667

In Python 3:
    >>> print(str(0.261666666666667))
    0.261666666666667

Change-Id: I4beed7aff7e89f891024975b9df9208c987dc87c
Merge "Python 3: fix test_sample_list"
Merge "client looking at wrong cacert argument name"
Merge "Supports bash_completion for ceilometerclient"