Fix for theme_button()

Adjusted the output for megatron_button. Now that we are not outputting
these as ‘button’ elements (earlier bug report), we don’t need to wrap
the element title. Fix for this issue:
https://github.com/ubc-web-services/Megatron/issues/21
Fix megatron_preprocess_table

megatron_preprocess_table was not passing classes as an array
Merge commit 'e096f25920fadfaa875c3da702d8253028684eb3'

* commit 'e096f25920fadfaa875c3da702d8253028684eb3':
  Fix for theme_button()
Merge commit '89a0184332ccd6237171168e0224891ddfab3918'

* commit '89a0184332ccd6237171168e0224891ddfab3918':
  Fix megatron_preprocess_table