Kepler

If kepler is currently in a branch, the change-to command should not update from the trunk. Once a branch is selected with the -Dbranch=xxx param, the build system should keep the current workspace in the branch until the user updated to another branch or the trunk. The build system should also print a banner alerting the user that he/she is working in a branch to avoid confusion.

this bug arose when we added several modules to the trunk. Matt was working in a branch (unknowingly) and when he ran 'ant change-to -Dsuite=kepler' it updated the kepler/module-info/modules.txt file from the trunk, but did not update the rest of the modules to the trunk so the build failed. The build-area was also running from the branch so the excludes file was not updated and would not allow him to build ptolemy.