Rename: OTmessage -> notaryMessage.
Rename: OTuser -> nymData.
Message/API rename: checkServerID -> pingNotary.
Rename: serverID -> notaryID (all variants).

Those changes were produced by:
find . | egrep "(cpp|hpp)$" | xargs sed -i -e 's/serverI[dD]/notaryID/g'
find . | egrep "(cpp|hpp)$" | xargs sed -i -e 's/ServerI[dD]/NotaryID/g'
find . | egrep "(cpp|hpp)$" | xargs sed -i -e 's/server_id/notary_id/g'
find . | egrep "\.proto$" | xargs sed -i -e 's/server_id/notary_id/g'