Upgrade OpenSSL library to 1.0.1i

Previous versions of the library contain several vulnerabilities:
https://www.openssl.org/news/secadv_20140806.txt

OS X: Fixes check for OpenSSL version

Fixes #606

Added definition of new rubies

Add 2.2.0-preview1

Show specific upgrade instructions based on environment

Add missing checksums to Rubinius definitions

Workaround for travis-ci/travis-ci#1719

On Fedora, this results in a nice "Fedora 19" identifier and doesn't
show the codename "Schrödinger’s Cat" which is otherwise contained in
`/etc/fedora-release`.

On Arch, this shows "Arch Linux" where previously we had no info for it
(for some reason, `/etc/arch-release` is empty).

http://www.freedesktop.org/software/systemd/man/os-release.html

Because ruby-build is both a Homebrew formula and an rbenv plugin, some
people end up with both installed. In these cases, executing
`rbenv install` vs. `ruby-build` might not use the same install. Users
end up being unsure where `rbenv install` is coming from and upgrading
it from the wrong location.

This detect whether ruby-build is contained in Homebrew or git and shows
upgrade instructions accordingly. Example:

    See all available versions with \`rbenv install --list'.

    If the version you need is missing, try upgrading ruby-build:

      brew update && brew upgrade ruby-build

`rbenv install` completion includes definitions from plugins

Before, `ruby-build --definitions` was invoked sooner than
RUBY_BUILD_DEFINITIONS was built up with paths from rbenv plugins.

[ci skip]

On FreeBSD 10, stop defaulting to MAKE=gmake

Sort Ruby versions when listing available definitions

Stable releases should now be sorted as a higher version than preview
releases or RCs. For instance:

- 1.9.3-preview < 1.9.3-rc1 < 1.9.3-p0
- 2.1.0-dev < 2.1.0-rc1 < 2.1.0
- jruby-1.7.0-preview1 < jruby-1.7.0-rc1 < jruby-1.7.0

Fixes #604

This detects when `/tmp` has been mounted with "noexec" mode and avoids
the cryptic error:

  ./configure: Permission denied

Hopefully the information provided will be enough for the user to know
that they have to change TMPDIR to another location.

It appears that regular `make` that ships on FreeBSD 10 is compatible
enough to build Rubies. This enables ruby-build on fresh FreeBSD
installs (which don't have `gmake` by default) without having to
explicitly set `MAKE=make`.

Closes #610

Now supports `-h|--help`.

This has the CI step verify the checksums for URLs that might have been
added or edited to build definitions in a pull request.

On FreeBSD, use the same approach as OS X with `sysctl`.

Make build output and log more useful

Fix `rbenv install --list` for definitions auto-discovery

The build definitions auto-discovered from rbenv plugins would
previously not appear in `--list` results due to discovery process
taking place too late.

`assert_success` doesn't accept an argument via stdin

This is useful info for when someone is pasting build output to our
issue tracker seeking support.