Skip doctests that require a remote server
Add support for REMOTE flag to doctests.
Document new REMOTE flag in doctests.  Remove out-of-date information
about doctest flags remaining in the output.
Mark some doctests as +REMOTE
Merge pull request #40 from mdboom/docs/disable-remote-doctests

Add REMOTE flag to doctests so we can disable tests that require remote data
Renamed doctest +REMOTE option to +REMOTE_DATA
Merge pull request #1843 from astrofrog/disable-remote-doctest

Skip doctests that require a remote server