Enable support of input groups within button groups

Created by: SmithSamuelM

BS3 use of display: table and table-cell breaks btn-toolbars. Using an input as part of an input group inside of a btn-toolbar always forces any following btn-groups to wrap to the next line. It appears to be a problem with using display: table

To fix it I had to revert to using display: inline-block for input groups and then adjusting the horizontal spacing.

It may seem like a good idea to use display: table-cell to get horizontal elements to snug up to each other but it breaks btn-toolbars and so is a bad choice unless you also fix up everthing else to work with display: table and table-cell. This is a regression from the behavior of BS2 and should be fixed.