support TFS checkin-policies
https://jira.codehaus.org/browse/SCM-750: support TFS checkin-policies

https://jira.codehaus.org/browse/SCM-750: support TFS checkin-policies
[SCM-750] support checkin policies
[scm-750] checkin policies
[SCM-750] checkin policies
[SCM_750]: extract const