Cleaned up entity.xsd

spelling correction from entitity to entity
also changed "a" to "an" since its before a vowel

Change-Id: Ie3bdd7038eed97c60a84e0b8715eb4b17df879a5
Cleaned up identity-concepts.xml

Extra "a" was removed, not necessary in sentence
An network was changed to "A" network
It should be "rights and privileges" rights plural
vs. right and privileges. Added the plural "s".

Change-Id: Id1103d3209b15b7cbef7a7337539d203486bc9c8
Revert "Add extension discovery to core API."

This reverts commit b72e8f129c4cf093b997104610075f3e7d515714.

It was discussed and decided that we should treat extensions as simply
links from the regular GET /v3/ calls.

Change-Id: Ia84fbd55f50d3fe7d9576b186c051743b4ef161a
Cleaned up tenant.xsd

An should be "A" since the next word doesn't start w/vowel
An boolean is incorrect, it should be "A"

Change-Id: I04d10f34777c51b1dde060009e68a29692c3c9da
Merge "Cleaned up tenant.xsd"
Merge "Cleaned up identity-concepts.xml"
Merge "Cleaned up entity.xsd"