Fix ruby engine detection such that it detects Ruby 1.8.7

Based on bundler's ruby engine detection:

https://github.com/carlhuda/bundler/blob/438ef20987951883cb5837d245eac9c517848b2d/lib/bundler/ruby_version.rb
Add note on how to build the jar and bundle
Add rake development dependency

This allows you to run:

    bundle exec rake

Before this change, this command failed with the error:
Gem::LoadError: rake is not part of the bundle. Add it to Gemfile.
Add Travis CI configuration file
Add Travis CI badge to the top of the README
Consistenly use double quotes in Rakefile
Cleanup trailing whitespace
Remove unused import.
Preparing for Unsafe-free CHMv8. Added an interface.
Copy-paste Unsafe using classes.
Remove all Unsafe usage from jsr166e.nounsafe classes.
Move CHM instantiation into a static method.
Add a Unsafe/no-Unsafe switch.
Crude testing setup.
Improve SecurityException detection.
Tweak the no-unsafe test case.

The no-unsafe TS::Cache test suite is now run by passing a TEST_NO_UNSAFE env var like this: rake test TEST_NO_UNSAFE=true.
Use the "factory" method to get keys.
Rescue from NoMethodErrors when objects "lie" about responding to <=>.

Fixes #19.
Bump TreeNode threshold.

Using TreeNodes means going into Ruby-land, which is actually slower than extra long Node linked lists.
Merge pull request #23 from sferik/travis-ci

Add Travis CI