Support creation of milestones

[cbeams]

Currently, ghi's support for managing milestones does not include creating them:

$ ghi --version
ghi version 1.2.0

$ ghi milestone --help
usage: ghi milestone [<modification options>] [<milestoneno>]
   or: ghi milestone -D <milestoneno>
   or: ghi milestone -l [-c] [-v]

    -l, --list                       list milestones
    -c, --[no-]closed                show closed milestones
    -S, --sort <on>                  'due_date' or 'completeness'
        --reverse                    reverse (ascending) sort order
    -v, --verbose                    list milestones verbosely
    -w, --web

Milestone modification options
    -m, --message [<text>]           change milestone description
    -s, --state <in>                 'open' or 'closed'
        --due <on>                   when milestone should be complete
                                     e.g., '2012-04-30'
    -D, --delete                     delete milestone

Ideally, ghi milestone would support creation, just as ghi label does.

See also #311.

[davidCarlos]

I will work on this issue.

[felipefialho]

Do you have news about it?

[gallexi]

The current code actually does this! Simply typing ghi milestone -m "some message" creates a new milestone named some message. You can also use --due to add the date.

Thing is, the current usage does not reflect it. I can update the usage to reflect the actual functionality.

[jakejohns]

@gallexi says this works, but i get the following

$ ghi milestone -m "some message"
Invalid request.

For 'properties/description', nil is not a string.

[gallexi]

Ah, it looks like somehow the -m "some message bit is ending up nil and not making it into the "properties/description" field. To be super honest I don't really have the bandwidth to look into this now, but if someone else wants to, that'd be awesome =]