Continuum ignores duplicate projects in forced and scheduled builds

When there are duplicate projects being built at one time, Continuum ignores the duplicates and only builds one of them. (See ProjectSorter.java) It prints a log message, but there is nothing visible in the web ui.

Continuum considers projects with the same groupId:artifactId:version as duplicates, so for example you can't built both the trunk and a branch with the same version in the one group (or even in different groups if they are on the same build schedule.)

It should probably warn if you add duplicates to a group.

If you click 'build all' and it is not going to build everything, it should tell you.

For scheduled builds there should be some indication of why a project was not built.