Implemented default error display for forms, updated session service, implemented basic layout of sign in page

@DuaneGarber take away's:
* home now redirects to /session is no session exists (first thing a new user should do is have to log in)
* added directive to handle form validation, along with some basic styling
* created a basic form layout

just run this guy and hit the session page to test form validation

for future reference, to apply my validation directive, simply use
```html
<input validate [required] [ng-pattern="/.*/"] [etc...] name="test">
```

`validate` will apply the validate directive, which maps the error messages to the error object generated by angular. you **MUST** define a name attribute, or it will display a fragmented sentence (though this would be eacy to fix in the future)