Create public function to check if cache needs update

move update cache check to public function
Bug fix, variable cache_file
add .gitattributes
add test
remove old files, add new test
change test
change test
change test
change test
change test
Merge pull request #67 from mimmi20/master-test

Master test
Merge pull request #63 from frederikbosch/master

Create public function to check if cache needs update
Merge branch 'master' of https://github.com/browscap/browscap-php