Added the first unit test for the string argument. Plus test of travis.
Added some new lines at the end of the modified files.
Added the update of the composer for travis in the before script statement.
Advanced a little bit more the php tests of String args.
Finished the test file for the string argument object.
Merge pull request #8 from karlito139/master

Added the begining of the tests of the programme using phpunit. Plus a travis file.