Added .mobile-box-layout class to fix Android bug

Usage: Declare .mobile-box-layout on a (outer-cell) when that cell contains .mobile-top and .mobile-bottom elements
eg. <td class="mobile-box-layout"> ... <div class="mobile-top"></div> ... <div class="mobile-bottom"></div> ... </td>

- Necessary to fix old versions of WebKit that don't support CSS display 'table-footer-group' (including Android OS), used by .mobile-bottom class
- WebKit bug causes contents of .mobile-top to not be rendered (as if it was set to 'display: none')
- Info: https://bugs.webkit.org/show_bug.cgi?id=17205 (http://stackoverflow.com/questions/8984032/table-header-group-table-footer-group-properties-doesnt-work-in-chrome)
Merge pull request #9 from jcphua/patch-1

Added .mobile-box-layout class to fix Android bug