"Resolve "Implement filesystem stores"

.gitignore

controller/northbound/server/role.go

controller/nucleus/deviceFilesystemStore.go

controller/nucleus/deviceFilesystemStore_test.go

controller/nucleus/errors/errors.go

controller/nucleus/pndFilesystemStore.go

controller/nucleus/pndFilesystemStore_test.go

controller/nucleus/sbiFilesystemStore.go

controller/nucleus/sbiFilesystemStore_test.go

controller/rbac/roleFileSystemStore.go

controller/rbac/roleFileSystemStore_test.go

controller/rbac/roleStore.go

controller/rbac/userFileSystemStore.go

controller/rbac/userFileSystemStore_test.go

controller/rbac/userStore.go

controller/store/filesystem-settings.go