Adjusting column titles as requested by Ken.

This commit attempts to address #6.

- increased the text size for the "Tap" and "Beer" column titles
- added "[IBU]" to the bitterness column
- added "[SRM]" to the Color column
- renamed "Level" to "Keg Volume"

/cc kencodes
#6 Changed "Keg Volume" tab

Changed "Keg Volume" column title to "Remaining<br />Volume"
Merge pull request #13 from philsc/ps.change_column_titles

Changing column titles and font size