UP-4112 Enhance impersonate to select target profile

## Features
* Selection drop down for impersonation profile
* Dynamic drop down of profiles based on what the system profiles are configured as
* Style buttons to be button group (using bootstrap)

Tracked in JIRA as [UP-4112](https://issues.jasig.org/browse/UP-4112).

## Deferred Weirdness
* Unimpersonation (logout of swapped) brings you back to your default profile, not necessarily the one you were on.
* Selecting mobile view redirects to default because you are on a desktop

## Screenshots
![image](https://cloud.githubusercontent.com/assets/3534544/2990214/5a0ce45c-dc6e-11e3-84d8-c75f9f4c8227.png)

![image](https://cloud.githubusercontent.com/assets/3534544/2990218/6927bc32-dc6e-11e3-9d69-6749d398edb1.png)