Fix the gemspec for padrino 0.11.
Fix string concatenations.
Merge branch 'fixes_for_slim' into padrino-0.11

Conflicts:
	lib/bootstrap_forms/form_builder.rb
	lib/bootstrap_forms/helpers/form_tag_helper.rb
Merge pull request #5 from scaryzet/padrino-0.11

Code update for padrino 0.11 (html_safe)
fix merge conflicts, more html_safe