Touch up Edit Attribute functionality

[aaronstrickland81]

• Remove the "required" checkbox (this will be marked in Equipment Type creation/editing, not in Attribute)
• Add "back" button which returns the user to the "Manage Attributes" page.
• Add optional regex field which should appear if the type "String" is selected
• Make the "Save" button inform the user that changes were made.
• Have the system return to the Attribute detail page on save, rather than remain on the edit page.
• Normalize terminology (e.g. "Visible" vs. "Public")