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
Adding a welcome email for new users.

Added the infrastructure necessary to support sending a email to
users when they sign up, either locally or by using an OAuth
provider. Also added a basic welcome message for new users.

Fixes #374
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
Added metrics for assigned/completed/archived tasks.

Previously, the user page only included open/closed metrics.
Now the results have been differentiated to show the different
types. Additionally, empty cells now show empty instead of 0/0.

Fixes #390
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.
Addressing concerns with prior commit.

* Adding a link to the system to the text notification.
* Removed unnecessary lookup for email address from preflight.
* Moved dup welcome email code into a helper method.
Made the task loop async, as suggested.

* The task counts per user are now async instead of looping
over the results.
* The volunteer column needed to support the open/assigned/completed/archived
breakdown.
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.
Merge pull request #403 from DavidEBest/devel-useradminextended

Added metrics for assigned/completed/archived tasks.
Removing unnecessary parameter to email generation.
Merge pull request #401 from DavidEBest/devel-welcomeemail

Adding a welcome email for new users.
increment to 0.0.23