Simplify handling of missing interpolation argument
Merge pull request #213 from nashbridges/simple-interpolation-missing

Simplify handling of missing interpolation argument
Release 0.6.5
Delete unused files from repo
Add exists? to check if a certain key exists in the translations
Move exists? implementation to Backend::Base, and Backend::Chain. Added test to lib/i18n/tests/basics.rb
Added dot-separated key tests for I18n.exists?
Merge pull request #182 from ndbroadbent/exists

Updated #69 - Add exists? to check if a certain key exists in the translations
Start a build matrix for the rails-3 gemfile
Specify all gemfiles for Travis to use
The I18n::MissingTranslation exception escapes key names for its html_message

Also added deprecation message for the :rescue_format option
Add I18n.locale_available? and enforce available locales

I18n.locale_available? looks for the passed locale in the
`I18n.available_locales` list.

---

Enforce available locales

When `I18n.config.enforce_available_locales` is true we'll raise an
I18n::InvalidLocale exception if the passed locale is available.

The default is set to `nil` which will display a deprecation error.

If set to `false` we'll skip enforcing available locales altogether (old behaviour).

This has been implemented in the following methods :

- I18n.config.default_locale=
- I18n.config.locale=
- I18n.translate
- I18n.localize
- I18n.transliterate
Bump version to 0.6.6
Remove reference to non exisiting CHANGELOG in the gemspec
Replace CGI.escape_html with CGI.escapeHTML which also exists in 1.8.7
I18n.enforce_available_locales delegates to
I18n.config.enforce_available_locales
Bump version to 0.6.7
Fix a naming clash between I18n.enforce_available_locales and I18n.config.enforce_available_locales

Renamed `I18n.enforce_available_locales` method to `I18n.enforce_available_locales!`
Bump version to 0.6.8
Tweak a few test descriptions