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.
link the latest ruby-build.$SEED.log and ruby-build.$SEED/ to ruby-build.latest.log and ruby-build.latest/ respectively
Use `patch --force` to ignore missing files when patching

From patch(1):

    -f  or  --force
       Assume that the user knows exactly what he or she is doing, and do  not
       ask any questions.  Skip patches whose headers do not say which file is
       to be patched; patch files even though they have the wrong version  for
       the Prereq: line in the patch; and assume that patches are not reversed
       even if they look like they are.  This option does not suppress commen-
       tary; use -s for that.

Fixes #555
Make `--patch` compatible with git diff patches

Filenames in git diff patches are prefixed by default by "a/" (source)
and "b/" destination. Such patches don't work with ruby-builds `--patch`
option since it internally uses `patch -p0`.

Prior workarounds were to use either an intermediate step:

    filterdiff --strip=1

or to generate the patch without the prefix in the first place:

    git diff --no-prefix ...

Now, git diff patches are detected by searching for this pattern:

    diff --git a/...

And `patch -p1` is used by default in such cases to strip the 1st
component of filename paths.

Fixes #521, closes #484
Fix patch passed via stdin in tests

[picture of I Have No Idea What I'm Doing dog]

https://travis-ci.org/sstephenson/ruby-build/builds/23435342
More portable invocation of `mktemp`

`mktemp -t ruby-patch`, although working on OS X, fails on Travis CI
with the message "too few X's in template".

https://travis-ci.org/sstephenson/ruby-build/builds/23436088
Correct the JRuby 9000 snapshot directory name.
Make the downloading message print the actual file name, not just the package name plus .tar.gz.
Merge pull request #559 from chrisseaton/fix-jruby-9000-package-name

Correct the JRuby 9000 snapshot directory name.
Merge pull request #560 from chrisseaton/downloading-filename

Make the downloading message print the actual file name, not just the package name plus .tar.gz.
Merge pull request #535 from Fleurer/patch/1

link the latest log to /tmp/ruby-build.latest.log
released 2.1.2
Merge pull request #566 from sstephenson/ruby-2-1-2

Ruby 2.1.2 is released!
ruby-build 20140509
added definition of 2.0.0-p481
Merge pull request #567 from sstephenson/2-0-0-p481

Added definition of 2.0.0-p481
Revert "Merge pull request #535 from Fleurer/patch/1"

This reverts commit d45f145197612f2b012d7dc3522949e719568371, reversing
changes made to 13de51105bcf927cbd01d05b69c695ddd3bfd1b9.
added definition of 1.9.3-p547
Merge pull request #573 from hone/ruby-1.9.3-p547

added definition of 1.9.3-p547
add rbx-2.2.7