Switching the order of the user list to show newest first.

Instead of ordering by id asc, it is ordered by createdAt desc.

Fixes #392
Made the admin dashboard tab first and default.

The dashboard panel should be the first in the list of tabs, and
as it provides the overview, it should be the default selected.

Fixes #396
Made the email address label on the login form customizable.

Open Opportunities wishes to specify the label as 'Official Government
Email Address', so I added an i18n hook for the field.

Necessary for 18F/midas-open-opportunities#26
Made the 'Volunteer' button always visible.

Previously, the volunteer button was only visible when a user was
signed in. Now, it is always visible; if the user is not signed in,
they are presented with the login dialog.

Fixes #259
Merge pull request #400 from DavidEBest/devel-i18nemail

Made the email address label on the login form customizable.
Merge pull request #399 from DavidEBest/devel-admindashboarddefault

Made the admin dashboard tab first and default.
Adding translations for more volunteer modal fields.
added state filter to browse
Merge pull request #393 from DavidEBest/devel-adminuserorder

Switching the order of the user list to show newest first.
Merge pull request #404 from brandtheisey/devel-state-filter

State filter to browse / search
Merge pull request #402 from DavidEBest/devel-alwaysshowvol

Made the 'Volunteer' button always visible.