Add script for checking system requirements.

The script can be run from the command line or a web browser. The output
will display which requirements are successful and which fail.
Merge branch 'requirements-check' into develop
Allow client code to get/set properties via element names.

Client code can choose to get and set object properties by using the
element name found in the XML.

Both lines below are valid:

$item->sku = 'A SKU';
$item->SKU = 'A SKU';
Merge branch 'element-names' into develop
Fix issue with using element names.

Setting property names with element names via the ctor was not working.
Ensure composer updates when running in travis.
Merge branch 'travis' into develop
Remove default parameters from BaseType::getParentValues.

Default parameters was allowing functions to incorrectly pass two
arrays. We need the code to fail if only was passed.
Update code for 0.0.5 release.
Merge branch 'release-0.0.5'