Base Styling of Button Classes

[sfrisk]

Making this an issue separate from Form elements in #6.

Following button styles to be included:

Basic Button
Modify by Type, Size

Button Group
Modify for Middle, Left, Right Buttons (Important if buttons have rounded corners)

States
Active, Disabled, Hover, Default

[sfrisk]

Also make sure button styles work on <input=button> and as well as