Support additional formats when transforming dates

[Brian Lewis]

The http Transformer transformer used to transform date strings into date objects supports the date formats as exported by ASP.

Extend this to support the date formats that appear in the googledrive meta data and in the SchoolInspection Xml:

specifically:

createDate=2019-07-26 19:03:51.0 GMT+03:00

createdTime=2019-07-26T16:05:20.709Z

‌

Note the latter format differs from the ASP format only in the milliseconds

[Brian Lewis]

feat(config): support date conversion from formats appearing in google drive and Survey Xml

Resolves #679

→ <<cset c2a8f5f4e152>>