Tweak formatting of a README.
Add license to gemspec.
Fix detection of installed rails versions

The regular expression for finding the installed versions of rails used to match gems like readcrumbs_on_rails instead of rails.
Therefore the script was unable to determine the correct versions of rails and quitted.
Upgrade test apps from Rails 4.0.1 to Rails 4.0.5.
Add test applications for Rails 4.1.1.
Add test support for Ruby 2.1.2.
Fix markup in bootstrap test apps.
Upgrade sqlite3 gem to make cross-Ruby testing work. Failed to support testing on Ruby 1.9.3.
Update READMEs.
Update changelog and version.