revised modal helper
model helper revised version accepts size variations modal id specification and js code injection
Validation error messages on bootstrap-themed forms are no longer hidden;
also applied Boostrap CSS to make them fit with the look of the page.

Signed-off-by: Judith Meyer <yutian.mei@gmail.com>
Including CSS
Update README.md
Undid changes to README
fixed missing bootstrap-modal class to main modal div
Merge pull request #748 from Sprachprofi/master

Validation error messages on themed forms are no longer removed
Merge pull request #737 from coppolaf/injectable-modals

Injectable modals