Install libyaml 0.1.5 for 2.x rubies also

This should plug the vulnerability to CVE-2013-6393 (and fix #504)
that can still occur in certain systems: If the ruby build process
couldn't find a libyaml that worked, it would build its own vendored
libyaml, which was 0.1.4 (and is vulnerable).

Instead, specify that the build always should install the latest
libyaml & build against that.
Update MagLev branch from master-1.9 to master
Merge pull request #504 from antifuchs/add-libyaml-to-2.x-rubies

Leaves rubies >= 2.0 vulnerable to CVE-2013-6393
Merge pull request #508 from johnnyt/maglev

Update MagLev branch from master-1.9 to master
ruby-build 20140214 :cupid:
Add mruby 1.0.0.
Merge pull request #510 from Red54/master

Add mruby 1.0.0.
Improve Java 7 detection

Java on most (all?) platforms directs `-version` output to STDERR.
Merge pull request #511 from cmattson/java7-detection

Fix Java 7 detection
added definition of Ruby 1.9.3-p545
remove build of libyaml, because bundled libyaml is already updated
Merge branch 'remove-libyaml-build'
Merge branch 'release-193p545'
added definition of Ruby 2.1.1
ruby-build 20140224
added definition of Ruby 2.0.0-p451
Merge branch 'release-200p451'
Merge branch 'release-211'
ruby-build 20140224.1
1.9.3 builds with performance patches.