Enhance ceilometer statistics command with --period

Currently, if don't specify query parameter in ceilometer statistics
command, ceilometer statistics with --period will not work. This change
is trying to fix this issue.

Change-Id: I8723bad11d5c452c2834e33df9bb01ebdc6ce9ce
Fixs: bug #1202658
Fix typo in help text.

Minor misspelling in alarm-{create|update} help text.

Change-Id: I1ddbaec42dda175a17d32229029c08d46e64151f
Ensure keystoneclient.auth_token is re-evaluated

Fixes bug 1207441

Force the re-evaluation of the keystoneclient.auth_token property
so as to avoid missing out on the in-built refresh logic when expiry
is imminent.

Change-Id: I8319e9e9a71e33e089fbe2fbc812d2b6c15da927
Handle case where os_auth_token is set to ''

Properly handle case (as in CLI) where os_auth_token is
set, but to an empty string.

Change-Id: I7e96bf22e2a91e0e3ec783b406fd05e4138860c8
Merge "Enhance ceilometer statistics command with --period"
Merge "Fix typo in help text."
Merge "Handle case where os_auth_token is set to ''"