Renamed XContentParser.Token named "t" to "token".

The name "token" was declared 191 times for XContentParser.Token
objects, while "t" was used only 6 times.
Renamed ClusterBlocks variable named "block" to "blocks".

"blocks" has been used 9 times for variable names of type
ClusterBlocks but block has been used only this case. It
seems to be a typo.