Allowing to have static x-axes in line chart

Allowing to define static time span for the line chart.

Change-Id: If2fdb87917c46504de9a04f2cafbcd7713f197b9
Closes-Bug: #1243716
Fix typo error in the comment

Change-Id: I6f0a7760022783a05d11258ab9b6f06d8ba5fbc0
Closes-Bug: #1279473
Merge "Allowing to have static x-axes in line chart"
Made Availability Zone mandatory for Aggregates

Apply the same max_length validation on update form
as well.
Change-Id: I169f45e003cd228a62e253dca4fa2d79b905024f
Closes-bug: 1357195
Merge "Fix typo error in the comment"
Merge "Made Availability Zone mandatory for Aggregates"