clarified "conflict with verb display"

resolve issue: https://github.com/adlnet/xAPI-Spec/issues/180
updated version # to 1.0.0
updated example signature based on new ver # in example statement
reference Semantic Versioning

Small change to actual requirements, mainly the declaration that we will conform
to Semantic versioning impacts future releases.
activity definition / metadata clarification
Yet another bunch of minor cleanups
Rephrased as per PR comments
Merge pull request #182 from bscSCORM/verbdisplay

clarified "conflict with verb display"
Fixed as per PR comments
Merge pull request #185 from bscSCORM/compat

Semantic versioning
Changes based on feedback

* Noted activity definition is optional (for clarity, noted that activity id is required)
* Noted activity definition properties other than name, description, and type only MAY be included (as opposed to SHOULD)
* Moved a line for flow
Optinal -> Optional
Merge pull request #190 from scara/v10_Yet_another_minor_cleanup

Yet another bunch of minor cleanups
typo
Merge pull request #194 from bscSCORM/typo

fixed a typo
Merge pull request #187 from bscSCORM/description

activity definition / metadata clarification
resolved merge conflict
Merge pull request #2 from bscSCORM/patch-1

Resolved merge conflict