Add links to mailing list and twitter
Use hash-style keyword arguments for path_to helper
Re-wording in CHANGES
Updated dependencies, removed dev gems
Use debugger instead of ruby-debug
Remove rspec deprecation warnings

stub! -> stub
mock -> double
Remove errant call to Sinatra.helpers in fixture
Removed built-in page caching implementation
Add Nesta::Config.fetch for user-defined config variables

Closes #136.
Nesta::Config.fetch raises if setting not defined
Run tests under 1.9.3 and 2.0.0 on Travis
Upgrade to Sinatra 1.4
Upgrade to rdiscount 2.1
Switch to Ruby 1.9 hash syntax
Use debugger gem in Gemfile template
Mention mr-sparkle in README and template Gemfile
Mention Ruby 1.8 has been dropped in CHANGES
Specify default when calling Config.fetch

Works like Ruby's Hash#fetch method.
Config::NotDefined inherits from KeyError

The thinking here is that when calling Config.fetch you might expect
that it'd raise KeyError (like Hash#fetch) does if the config setting
you want isn't defined. So we do.
Nesta::Config from_(environment|yaml) raise NotDefined

Previously these methods returned nil, which encouraged them to be called one
after the other in a boolean short-circuit style, leading to subtle bugs
in the way config values that evaluated to false were handled.

Raising an exception has also allowed needlessly complex conditional
statements to be simplified.