Added relevant links to header (closes #12)
Renamed document title
Fixed up abstract

Made is clear that this API is generic, not just for screen locking.
Linked to Use Cases document (closes #13)

Note that the [[WAKE-LOCK-USECASES]] will automatically start linking
once the UC document is published on Thursday.
Fixed up conformance section.
Removed redundant text (closes #19)
Removed a bunch of redundant text
Removed bad example (closes #18)