Introduced email verification service

- Introduced service interface and default service
- Used in CM_FormField_Email (refactoring)
Added KickBox email verification service

- Installed php client
- Rejected disposable addresses
- Rejected addresses with poor Sendex if no SMTP check is possible
- Added tests
Made KickBox service configurable

- Added tests
Merge branch 'master' of github.com:cargomedia/CM into issue-1328
"Updated" KickBox to ~1.0.3
Renamed CM_Service_EmailVerification_Default to CM_Service_EmailVerification_Standard
Handled the case where you have no KickBox credits any more

- Added test
Added tests for CM_Service_EmailVerification_Standard
Merge branch 'master' of github.com:cargomedia/CM into issue-1328

Conflicts:
	composer.json
Cached KickBox response
Fixed KickBox caching

- Added client configuration to the cache key
- Used a different email address in every test
Removed usage of CM_CacheConst for modularity
Merge pull request #1328 from fauvel/issue-1328

Add KickBox service