Update to the new Travis CI infrastructure.

[xzyfer]

http://docs.travis-ci.com/user/migrating-from-legacy/#Why-migrate-to-container-based-infrastructure%3F

[saper]

Er, looks like we are not getting the compiler we want. My suggestion for priority: low :)

[saper]

According to "C++0x/C++11 Support in GCC" table template alias feature should be supported in g++ 4.7. Which compiler are we getting in the end?

Interestingly, libsass seems to compile just fine with the default gcc 4.6.3. So the new V8 is quite picky about the compiler. Can we ask for g++ 4.7 only for io.js 3 in the new infrastructure? (besides it does not seem to work)

[xzyfer]

It looks like I can install gcc/gcc 4.7 but I can't alias gcc/g++ to the newer versions without sudo.

I agree this isn't a high priority. I just wanted to take a run at it before going to bed. The slow Travis times are also starting to bug me.

[saper]

That should be relatively easy, then. If the compilers are named gcc47 and g++47 we just need to call /usr/bin/env CC=gcc47 CXX=g++48 LINK=gcc47 LINKXX=g++47 npm install

[xzyfer]

Looks like this works now. I've some intermittent Travis failures which don't instill me with confidence.