Update composer.json.
Update composer.json.

Move misumirize/pre-commit-hook to dev dependencies.
Tweak description and keywords.
Add test script.
Bump minimum required php version to 5.5.9.

jjpmann/real-magnet-sdk,pmatseykanets/real-magnet-sdk,pmatseykanets/real-magnet-sdk,jjpmann/real-magnet-sdk