Change server protocol of the ruby-lang.org server in the MRI definitions from HTTP to FTP

Closes #375.

use Homebrew openssl if available

Fixes #343, references #367

making checksum comparison case insensitive

Add install script for Maglev 2.0.0 dev (the branch with 1.9 support)

Fix the has_broken_mac_openssl function for the pre-release version of OS X

Treat the openssl 0.9.8(r|x) bundled with OS X as broken library. So the ruby-build will download and build the latest one.

Added JRuby 1.7.4

Replaced 1.9.3-p426 with 1.9.3-p429 definition (p426 was yanked after release due to build issues)

1.9.3-p426 was deprecated by 1.9.3-p429 since it won't build on RHEL6
systems (and others?)

added 1.9.3-p426 and 2.0.0-p195

Allow define RUBY_CONFIGURE_OPTS on rbx configure

The configure of rbx can take a RUBY_CONFIGURE_OPTS. You can by example
use the `--skip-prebuilt` OPTS

Restore -O3 default when we build with clang

Unable to clone ruby-build from behind firewall

Fixes #267

Fixes `rbenv install` in a directory with a .ruby-version file that specifies ree

* Decrease likelihood of cache collisions
* Avoid file:// urls (and therefore the need to escape)

if RUBY_BUILD_CACHE_PATH is set, create and maintain a local bare git
repository in this location.  The name of the git repository is based
on the git URL, so it will be shared between branches.