[core][fix] Add InstallDefaultTheme feature.
[core][fix] Service module inherit Error module
[core][fix] Install default theme on widget init
[doc][fix] Fix .htaccess
[core][fix #36] Fix : Modal doesn't scroll since Bootstrap 3.2.0
[core][fix #38] CLear Css error on fields when errors are cleared.
[doc][fix] Improve grammar and fix typos