Update and rename CONTRIBUTING to CONTRIBUTING.md

Updated to be compatible with github markdown mode.
Merge pull request #21 from niedbalski/master

- Formated to be compatible with markdown
- Renamed CONTRIBUTING to CONTRIBUTING.md
juju/testing: close clients before API server

There's a bug in JujuConnSuite where the teardown
of clients occurs after the server is destroyed.
This sometimes causes the client's Close method
to error, because it cannot write the websocket
0xFF frame.

Fixes https://bugs.launchpad.net/juju-core/+bug/1293697
Merge pull request #23 from axw/lp1293697-jujuconnsuite-closeorder

There's a bug in JujuConnSuite where the teardown
of clients occurs after the server is destroyed.
This sometimes causes the client's Close method
to error, because it cannot write the websocket
0xFF frame.

Fixes https://bugs.launchpad.net/juju-core/+bug/1293697
state/api{,server}: more FullStatus API data

The FullStatus client API response now includes a new Relations field
containing relation and endpoint data.

Machines and units now also have a StatusData map in the FullStatus
response which holds extra status information that a client may choose
to use when displaying status. This was already being created but not
passed through the client API. The returned StatusData map is
whitelisted to prevent unintentional leakage of internal-only data of
over the API.

The client API test scenario has been extended to include a case of a
unit with an error with extra status data included.

Apart from providing opportunities for showing more detail in juju
status output generally, these new items will be used to display
relation details in the "juju status" output when a relation hook
fails (LP #1194481). This change will be done in a different branch.