add decimal and float range query

extending @akm integer range query code to float
and decimal fields
Merge pull request #1530 from thiagobrandam/decimal_and_float_comparison

Add decimal and float range query
Revert "use safe_send instead of send for association's value"

This reverts commit c1dd985b34d5159cfd2b636d0f726e938441c49b.
Ckeditor fix

See https://github.com/sferik/rails_admin/commit/e97f4fadff17b77e65c452be3ac4314adeb16748#commitcomment-2645547
Ckeditor [ci skip]

Remove old instances if found
fix the build