#5 Allow classes directoryfor the classpath

[Sushil Sureka]

Model Editor can import classes only from a jar
currently. If a classes directory is added in the
classpath (containing domain model classes) in the
model editor, then the classes are not imported while
perfomring "Import from Classpath" action.

Since most of the time the developer only builds the jar
towards the end of the project, allowing classes to be
imported from the directory(in addition to jar) would help
productivity.