changed about/version to an array

In order to leave the door open for a future LRS that supports 1.x.x as well as 2.x.x, but without a 2.x.x specification __requiring__ 1.x.x support, making the about/version property an array so that an LRS may list the versions it supports.
[] -> Array, xApi -> xAPI

In response to feedback:
* changed string[] to Array of string
* changed xApi to xAPI
about version

Updated about version to allow indicating support for future and prior versions
Merge pull request #213 from bscSCORM/about

changed about/version to an array