uniform CHANGES format for version 0.5.5
fix PL-PGSQL error when restoring a database backup

When restoring a backup on Postgresql 9.x following error was occurring:
ERROR: An error occured while calling pg_restore: pg_restore: [archiver (db)]
Error while PROCESSING TOC:
pg_restore: [archiver (db)] Error from TOC entry 199; 3079 11733 EXTENSION
plpgsql
pg_restore: [archiver (db)] could not execute query: ERROR:  syntax error at or
near "EXTENSION"
update CHANGES for 0.5.6
update TODO
Merge changes for 0.5.6 from branch 'develop'
set m2ee module version to 0.5.6
Merge branch 'master' into debian
Update changelog for 0.5.6-1 release