enabled travis-ci

Results first:
http://travis-ci.org/jakoch/easyrdf/builds/3923838
This is the Travis report for my fork of EasyRdf.

If you pull this request, you need to register an account on travis-ci.org and fetch the api-token.
With the token you can setup the travis-hook for your njh/easyrdf repository on github manually.

This enables automatic runs of the EasyRdf TestSuite, when 
a) you push 
b) a new pull-request is incomming.
(So you can see, if the PR breaks something, before actually merging it.)
The travis details are attached to the pull-request comment on Github, you might have seen that before. Also the travis-ci bot sends the short-report to #easyrdf on freenode.

List of Changes:
- added composer "vendor" folder to .gitignore
- added phpunit.travis.xml
- enable coverage reporting via logger in phpunit.travis.xml
- removed "repositories" section from composer.json. that would mean that easyrdf has a 3th party vcs repository dependency to easyrdf itself (if added in the "required" section).
- adding travis build status of master branch to readme.md
- added fetching and exec of composer
- added fetching and exec of php-cs-fixer for PSR2 checks
- modified makefile to not run lint on the makefile itself, only on php files.
  used "--" = end of options; "*.php" glob
  got this from http://www.kernel.org/pub/software/scm/git/docs/git-grep.html
- modified makefile to "always terminate successfully", when running tasks "check-whitespace" and "check-fixme". without exit code travis will run forever.
- added make lint, check-whitespace and check-fixme to travis.yml
- added development dependency "phpunit" ">=3.5.15" to composer.json (this will use phpunit 3.7.*)
- added irc-bot reporting to #easyrdf on freenode
- added underscore to PSR-0 prefix