Fix test failing when run close to the end of the day.
Prefix `gid`/`sgid`/`global_id`/`signed_global_id` with to_.

This prevents clashing method names. For example apps modelling file system
permissions might have a group id aka gid accessor.

This also clarifies global ids as a conversion like `to_s`, `to_a` etc. methods.
Encode expiration as iso8601 in UTC timezone.

Allows subsecond expirations to be encoded, which would be helpful for
something like API requests.

This also ensures a specific encoding format for timestamps. Previously
the encoding was left up to the serializer which might not roundtrip
time like objects.
Merge pull request #37 from kaspth/expiration-encoding

Encode expiration as iso8601 in UTC timezone.
update global id version
Merge pull request #41 from seuros/patch-1

update global id version
Configure the notifications
Implement URI::GID

Codify the encoding of an app unique reference to a specific model by building
on the foundation of URI::Generic.

Closes #18
Detailed usage in README
Add params to URI::GID to store simple metadata as query parameters.
Merge pull request #44 from rails/gid-query-params

Add options to URI::GID to store simple metadata as query parameters.