Quota/limit graphs now work in IE

IE has only parital support for html5 dataset. Here proposed solution
accesses the custom attributes via JQuery.

Fixes Bug #1195500

Change-Id: Ie1832db4671f5907d0cb0da50b0bbbd597f1b16d
Sort tenants in tenant dropdown, per #1234993

Change-Id: I6e2fd3868ac3b0b0d1704bf034e6546726fda5c3
Closes-Bug: #1234993
Disable H803 check.

H803: Git commit title should not end with period.

I don't think we really care whether a commit title ends with a period
or not. Certainly not enough to warrant patches failing checks and
wasting people's time and CI resources.

Change-Id: I52fd73c35545943b1a7e2cec62ddb52a5f90a24b
Closes-bug: 1236621.
Refactor horizon TemplateLoader

Here we can use `with` statement to keep
horizon code clean.

Change-Id: I98ffc3fbcb6892a3739f2de1936c54e868f8908f
Merge "Sort tenants in tenant dropdown, per #1234993"
Merge "Quota/limit graphs now work in IE"
Fix import keypair help text

The existing text was just copied from the create keypair view.

This commit adds a bunch more help text and instructions for creating
an SSH keypair from a terminal.

Change-Id: I43cb31ac0fcf46dbd1c607687810caf0e18ffde4
Closes-bug: #1237264.
Merge "Refactor horizon TemplateLoader"
Merge "Disable H803 check."
Merge "Fix import keypair help text"