Merge branch 'origin/master'
BS-2719 : Migration Look & Feel

Changes :
- Add new folder for feature migration
- Create Groovy script
- Refactor code
- Create SQL scripts (for all databases)
Merge branch 'origin/master'
Add migration from 6.1.0 to 6.1.1, from 6.1.1 to 6.1.2, from 6.1.2 to 6.2.0
Merge branch 'origin/master'
Remove scripts to change version of platform. It's done now in MigrationRunner.groovy.
fix missing Database folder when there is nothing to do for database
Merge branch 'master' into BS-2037

Conflicts:
	bonita-migration-distrib/src/main/groovy/org/bonitasoft/migration/core/MigrationRunner.groovy
BS-2886, add integration tests for 6.2.0
fix migration of bonita home client
Merge branch '6.1.0_to_6.2.0'
Merge branch 'master' of github.com:bonitasoft/bonita-migration