Add coding standards / Add travis configuration to check it

Hi @cdujeu,

As many part of the code aren't well formatted (tabs on one line, spaces on another, CRLF or LF depending on the file, trailing spaces, ...), i'm proposing to use coding standards for ajaxplorer.
To check/correct the conformance automatically, i'm using php-cs-fixer.
To automatically check future commit and pull request i'm suggesting https://travis-ci.org/ (ultra easy to use, and integrate nicely with github, see the red cross on my commit line)

The travis build will not pass for now, as we haven't apply the coding standards for now.

See https://github.com/fabpot/PHP-CS-Fixer#usage  for the list of available fixers.
I can add/remove fixers as you wich.

We will also be able to run unit test with travis.

To activate it (1 min), http://about.travis-ci.org/docs/user/getting-started/ (for the step 3 simply merge my PR).