This change allows instance property overrides to be created without
deleting all the other instance properties by using the REST endpoint
correctly. It also allows empty property fields to be submitted to
remove the property.

Firstly the PUT and POST methods were the wrong way around, so they've
been swapped. Secondly, the POST method didn't allow empty fields, which
meant that instance property overrides couldn't be removed. To stop
this, empty properties are now treated as properties to be removed.

Signed-off-by: Matt Gill <matthew.gill@live.co.uk>

Added some javadocs for the class methods, and made a minor refactor to
one method signature.

Signed-off-by: Matt Gill <matthew.gill@live.co.uk>

The page title didn't have the parameter filled.

Signed-off-by: Matt Gill <matthew.gill@live.co.uk>

The @NotMicroCompatible and @SincePayara annotations should be inherited
when abstract test classes are annotated with them.

Signed-off-by: Matt Gill <matthew.gill@live.co.uk>

This commit adds a set of tests for the system-properties endpoint of
the REST management interface, to make sure that it responds correctly
to PUT and POST requests.

An arquillian extension has been added to allow temporary instances to
be created for the purposes of tests.

Signed-off-by: Matt Gill <matthew.gill@live.co.uk>