Add more starteam commands

• Testcase included:

  yes

Add checkin, tag, add, diff, status, and update

Here are the status of Starteam implementation

Known limitations:
=================

• Starteam's CLI interface does not accept relative path of a file in a subdirectory
  (ie xdocs/index.xml, etc). To make it generic, Whenever there is a need to
  handle a subset of files in a directory (ScmFileSet with exclude or includes are set)
  I have to issue individual command line for each file at the targeted subdirectory.
  So i will be slow if one unintentionally sets 'includes' as */* for a large source tree

• Starteam's CLI does not have interface to create SCM folder/directory, therefor
  Add command will fail when the add file is in a folder that is not existed in repository

• No TCK tests are used

checkout:
=========

• Does not support checking out a subsets of a directory

checkin:
========

• requires maven.scm.message

• use maven.scm.issue system property until maven-scm-api
  supports this feature (SCM38)

diff
====

• Dump starteam diff output to a file
• Parsing code completes
• Probably not usable

update
======

• Throws error when local file is modified (ie no merge for modified file during udpate)

add
===

• starteam folder must be precreated. StarTeam's stcmd does not support
  creation of folder.

• use maven.scm.issue system property until maven-scm-api supports this feature (SCM38)

tag
===

• Does not support tagging a subsets of a directory

status
======

• Does not support checking status of a subsets of a directory.

changelog
=========

No change to orignal code, just add finishing touch