Mirror Ball

This long overdue release of Scrolls brings it up speed with modern Ruby releases, improves the codebase and overall provides a better platform for further development.

After years of poor maintenance, Scrolls should now be usable again on recent versions of Ruby. In order to bring it up to speed, a number of backward incompatible changes were made:

• Scrolls#global_context is no longer mutable (see #54 and #71)
• Scrolls is now initialized using Scrolls#init (though it doesn't have to be if the defaults are enough)
• Scrolls#log_exception has changed to the following method shape (see #60):

Scrolls.log_exception(exception, data)

• Drop support for Ruby 1.8.7 and 1.9.3 (though it may work on the latter)

Additional changes include:

• Added functionality to escape keys of log data (see #67)
• Cleaned up codebase organization
• Fixed tests
• Fixed thread local context in recent Ruby versions
• Don't fail with nil error if unknown log level used (see #65)

The documentation has been mostly updated as well, though I plan to rework it all in the future.

I apologize for taking this long to bring the codebase up to speed and the overall lack of communication around the library. If there are still any users out there, thanks for your patience. I hope this release sets us up to add some much needed features (improved parsing, JSON output support, etc) soon.