Use underscores instead of camel-casing for date formats

[clintongormley]

The date formats stand out as one of the few place we use camel casing, eg strictDateOptionalTime

These should be changed to strict_date_optional_time etc

[bookshelfdave]

@clintongormley It looks like the formats have been updated in the Joda class already, is this simply changing tests and docs to reflect these changes?

[clintongormley]

@metadave It's the stringification which defaults to camelcase. Try:

PUT my_index/my_type/1
{
  "date": "2007-01-01T01:00:00Z"
}

GET my_index/_mapping

Don't worry about the docs, I'm reworking those in a bigger change