* Pull JSON schema from openmobilityfoundation repo

Since github.com/CityOfLosAngeles/mobility-data-specification
redirects to this new repo.

In addition, account for folder changes with the 0.4.0 tag.

* min MDS version goes to 0.3.0
* max MDS version goes to 0.5.0 (exclusive)

fortunately this wasn't a problem as the list
is eventually converted to CSV string

* docs about use of old start_time (status_changes), min_end_time/max_end_time (trips)
* docs about use of new event_time (status_changes), end_time (trips)
* version-based date formatting: unix for < 0.4.0, iso8601 hours for > 0.4.0
* raise when required params not given

no longer supported for status_changes and trips

since events has the same structure as status_changes,
introduce convenience methods for loading into status_changes table

* add required param checks
* format to Unix millisecond timestamp for querystring

* adding config file
* fix line lengths
* fix spacing
* fix unused imports
* fix spelling

the /events schema uses status_changes as the item key

handle cases when a parsed Version instance is compared with an
unparsed version str

technically 0.4.0 requests for status_changes and trips
may still use paging, so make the distinction

mds.Schema instances may be useful on their own, without an underlying
schema document from GitHub.

This change introduces a delay to acquire the schema document
from GitHub only when it is first needed (e.g. property access).

Early acquisition can be forced with keyword arg on init.

a more descriptive name for what this key is

* allow seconds or timedelta params
* randomize for missing param instead of 0
* correct new_date calc so that (date + min_td) <= new_date < (date + max_td)

* reusable (internal) class methods for 0.4.0 and 0.4.1
* fix a few checks for vehicles (valid for >= 0.4.1)