First pass on generation X-Request-Id headers

- RequestID helper class to generate uuids
- Setting headers client-wide to include request-ids
- Turning on the ActionDispatch::RequestId middleware on the server
using ActionDispatch::Static as our insertion point, Rack::Lock is gone
expanded the characters allowed in a X-Request-Id
extended ActionDispatch::RequestId to allow more characters in value

simplied client_id code; corrected request_id code to work with
inheritence
save off the request-id, show it in the error message
Request-Id header tests
tests for displaying Request-Ids in client errors
Extracted RequestId; provide way to use the same generated/custom uuid
rdoc for the RequestId usage
formatting
wording
tests for ActionDispatach::RequestId extension
removing constants collision on UUID_REGEX_FORMAT
formatting
added instructions for use of the `request_id` mechanism
wording
wording
wording
Merge pull request #50 from att-cloud/request_id_header

X-Request-Id header