Use "System Small" fonts in BundlePreference table

By using a smaller font size in the bundle table we can show more of the bundle description. Also, it minimizes the amount of resizing of the pane we have to do to see the entire description string for most of the bundles.
Save VariablesPreferences.xib with Xcode 5.1.1 (5B1008)
Use "System Small" font in VariablesPreference table

Since variable strings can be very long and we reduced the font size in the bundle table, let's be consistent and use a smaller font size here too.
Add search field to Bundle preference pane