Dev mode multi module - automate workaround to install ear project to .m2

[ericglau]

If the module containing Liberty configuration (specifically, the module without downstream dependencies) has packaging type liberty-assembly or pom and depends on a module of type ear, the user currently needs to install the ear project to the .m2 directory once before running dev mode:  mvn install -pl <ear-module> -am

Dev mode should try to automate this workaround to install the ear project (unless the ear artifact already exists in .m2) before starting dev mode on the liberty-assembly or pom module.

[scottkurz]

The #1570 fix addresses this problem without adding/purging from the local .m2 repository.