Merge pull request #20 from tristanlins/master

Now it is possible to remove a package, that is not yet installed.
Improve "composer output" output.
Add full package name search support.
Fix redirect to database update tool in contao 3.
Reformat code.
Only prefer dist packages, if neither git, mercurial or subversion available.
Send to database update after package update.
Improve installed package listing of dependencies.
Catch RuntimeExceptions and output them as TL_ERROR message.
prefere dist, possible values: source, dist or auto
Merge pull request #27 from dominikzogg/preferedist

prefere dist, possible values: source, dist or auto
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.
Improve environment check and add check for curl. fixes #21