Bug 651 - cleanup eclipse errors in openflowplugin

- To avoid devs from having to run the IDE profile so eclipse can see the yang
generated source files, the yang source files are now generated under src/main/yang-gen-sals
or src/main/yang-gen-config instead of target/target-ide.

- The maven-clean-plugin was moved to the ofp parent pom and removed from
all child poms where it was specified. Thus, it will be automatically run for all
projects. The plugin's execution will clean all xtend and yang generated source dirs.

- The build-helper-maven-plugin was also moved to the parent pom and removed from
all child poms. It will automatically run for all projects and no longer needs to be
specified in child poms. The plugin's execution will created eclipse source folders
for all xtend and yang generated source.

I also removed two occurances of "&gt;" which seemed extraneous ... but perhaps I'm unaware of some pom.xml magic?

Change-Id: Ie99e141e55e03a3a3ebce3743624e7bea6e42e7b
Signed-off-by: jameshall03885 <ghall@brocade.com>