OS X: Fixes check for OpenSSL version

We only care about Apple's OpenSSL when checking the version.  Any
other OpenSSL that happens to be in the PATH doesn't matter.
Add link to suggested build environment to README
Merge pull request #603 from wjordan/patch-1

Add link to suggested build environment to README
Add test for ruby-build definitions
Support changing RUBY_BUILD_ROOT

This is to allow specifying an alternate path where `share/ruby-build/*`
definitions reside. Useful in tests as well.
Extra definitions paths via RUBY_BUILD_DEFINITIONS

This is a colon-separated list of directories that will get searched for
build definition in order from left to right.
Merge pull request #613 from sstephenson/definition-paths

Support extra definitions paths via RUBY_BUILD_DEFINITIONS

Closes #609
Add rbenv-install tests
Auto-discovery of build definitions from rbenv plugins

The `share/ruby-build/` directory from each rbenv plugin, if it exists,
is added to RUBY_BUILD_DEFINITIONS automatically during `rbenv install`.
add ruby-1.9.2-p330
Merge pull request #615 from hone/ruby-1.9.2-p330

add ruby-1.9.2-p330
Merge pull request #614 from sstephenson/rbenv-plugin-definitions

Auto-discovery of build definitions from rbenv plugins
Read ruby-build revision from git if available

But don't assume that RUBY_BUILD_ROOT is where ruby-build's own files
reside, since RUBY_BUILD_ROOT can be overriden with alternate definition
files location.
Faster clone of Bats in CI

Avoid cloning the whole project's history which we'll never need
Merge pull request #612 from sstephenson/git-revision

Read ruby-build revision from git if available
add jruby 1.7.14 build
Merge pull request #620 from patricknavarromahoney/master

add jruby 1.7.14 build
add jruby-1.7.15
Merge pull request #624 from chulkilee/jruby-1.7.15

add jruby-1.7.15
ruby-build 20140905