add schemup dependency, add functions to get schema config & load migrations
add intial migration files
add migrate & snapshot functions
start versioning internal tables, check schema on startup
allow skipping schema check by a flag, or a config option

There are 2 ways to bypass the schema check:
- Adding the command-line flag --skipSchemaCheck
- Setting the option config["schema"]["check"] to False
add migrate & snapshot commands
don't try creating tables for postgres/mysql inside
warp.common.store.setupStore (schemup handles these now)
print a message instead of crashing when the DB is not supported by schemup
fix some sub-commands wrongly inheriting options
add some explanation in sample project's config file, more messages
during migrations, and "migrations" dir for skeleton site
don't support mysql migrations (until schemup implements a reasonable work-around for mysql non-transactional DDL)