Check for php version. fixes #22
Use local installed composer instead of phar. Preparation for #18
Fix the internal search, fixes #28 and #25.
Rework search for package details to use internals.

According to #28 and #25
Make the package name linked to details page in search results.
Do some code reformat.
Rework and cleanup the internal structure of ComposerClientBackend.
Remove the cvs detection and handle prefer-dist via config.