change Metadata#create/update/delete fn from async to sync
add upsert function to metedata
Merge branch 'fourq-metadata-sync-change' into metadata-sync-change
update browserify related dev package version
change upsert method to sync and fix parameter type annotation
fix typo in switch condition to check browser env loading
add metadata upsert test case
remove async metadata CRUD call from tests
add version check when calling metadata async api
Merge pull request #60 from jsforce/metadata-sync-change

Change Metadata#create()/update()/delete() fn from async to sync