Change README format and update instructions

 - Use simpler text formatting instead of Markdown.
 - Add Composer installation instruction.
 - Update installation instruction in general.
 - Add contributors
Add empty line at the end of file

As per coding standard
Update Docblock email and copyright
Fix required Kohana version in composer.json

Be more strict about required Kohana version.
Follow the PSR-0 standard

Kohana 3.3 added the PSR-0 support.

Rename files by following the standard.