Update to Gradle 2.0

http://www.gradle.org/docs/current/release-notes
nodejs 0.10.29
Merge pull request #344 from GrahamCampbell/patch-1

nodejs 0.10.29
Updating nvm to v0.11.2
Merge pull request #345 from ljharb/update_nvm_0_11_2

Updating nvm to v0.11.2
Update to nvm 0.12.0
Merge pull request #346 from ljharb/update_nvm_0_12_0

Update to nvm 0.12.0
Improved JRuby options.

Changes are as follows, with justification:

* --server to --client

--server is really only useful on long-running processes...longer
running than a test build. Tests are also a worst-case scenario
for optimization, since most code will only run once or a few
times. --client provides the fastest startup and shortest warmup
time with reduced long-run performance, making it a better choice
for test runs.

* Add -J-XX:TieredStopAtLevel=1

On 64-bit and newer JVMs, the -client and -server flags are no
longer honored. Instead, the JVMs either run server all the time
or a "tiered" compiler that combines -client and -server. This
flag forces that tiered compiler to only do client-level
optimization, equivalent to the fast-starting -client mode.

* Remove memory setting

It *is* true that the JVM itself defaults to a 64MB heap limit,
but JRuby already adjusts that to 500MB. This flag is actually
reducing available memory.

--

I believe these flags will work well on all recent JRuby versions
(within the last few years) and all Hotspot-based JVMs (OpenJDK,
Oracle, IcedTea) as far back as the 1.6 line.
Merge pull request #347 from headius/better_jruby_options

Improved JRuby options.
Upgrade php to 5.4.31 and 5.5.15
Use mongodb.org server to pull down packages

As a side effect, the installed version is now the latest
(which is 2.6.3 as of this commit) and this commit therefore
fixes https://github.com/travis-ci/travis-ci/issues/2246.
Merge pull request #349 from GrahamCampbell/php

Upgrade php to 5.4.31 and 5.5.15
Install PyPy before PyPy3, and create alias pypy3

See https://github.com/travis-ci/travis-ci/issues/2583

By changing the order, the 'pypy' binary in the pypy-2.3.1 will
be installed as 'pypy' in the default `$PATH`, instead of
that found in pypy3-2.3.1.

We also create a new alias `pypy3` which will point to the
_hard-coded_ PyPy3 binary, so that `tox` users can still use it.
There is a [ticket for PyPy](https://bitbucket.org/pypy/pypy/issue/1796/pypy-pypy3-in-the-same-path)
that will make it unnecessary to do this linking, but until then,
we will need this ugly hack.
Remove PyPy 2.2.1
Install 'wheel' by default for Python runtimes

Fixes https://github.com/travis-ci/travis-ci/issues/2065
Link correct binary
Move symlinking inside the each loop

So that #link is less hard-coded
Merge pull request #351 from travis-ci/ha-bug-ci_2583

Set up PyPy symlinks so that PyPy-2.3.1 is default, and PyPy3-2.3.1 is available as 'pypy3'
Avoid overwriting existing 'pypy3'

If the issue is fixed upstream, we should remove this hack.
Install 5.5.9

On Trusty (14.04 LTS), the default version provided is 5.5.9,
and some users prefer to stick with that version.