change module install dir to not be split into separate fac, reg, inst subdirs. Still need to fix schema building and env class and dynamic_loading class correspondingly.
made Env::ListModules more robust and include CYCLUS_MODULE_PATH env var dirs in search. Made BuildMasterSchema not care about model type namespacing subdirs.
Merge pull request #619 from rwcarlsen/module-install

change module install dir to not be split into separate fac, reg, inst subdirs