The UI for selecting time ranges produces nanosecond-precision times
for the template variables in the absolute time range. The regex for
absolute time ranges previously did not account for this precision,
which caused it to break.
This updates the regex to consider the nanosecond parts of an
RFC3339Nano timestamp and updates the associated tests. The Gobular link
has also been updated to a fresh playground used to debug this issue.
Previously, users of the :interval: macro were restricted to using a
relative time range in their queries, or the :dashboardTime: macro. This
permits users to also supply an absolute time range in the form of:
time > '2017-01-01T00:00:00Z' and time < '2017-06-01T00:00:00Z'