PSR-2 coding standard

See: https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md
add phpunit as dev dependency in composer.json
unlink in tests should be handled via setUp() and tearDown()
fixed relative path issue within tests
(empty) phpdoc added for all unit test methods
sleep time in all unit tests reduced to 1 sec
changed phpunit setting 'strict' to true
major refactoring
PSR-2: leading underscores removed

* Property names SHOULD NOT be prefixed with a single underscore to indicate
  protected or private visibility.
* Method names SHOULD NOT be prefixed with a single underscore to indicate
  protected or private visibility.

https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md
moved Jobby and all tests into \Jobby namespace
add authors to composer.json
fix code example in README.md
add more unit tests for \Jobby\Jobby
travis integration - first try
add travis build status in README.md
composer.lock updated
proper escape the name for the lockfile
even more unit tests
improved error handling and locking
lock handling moved from BackgroundJob into Helper