CAS-1286: Extract the OAuth client support in its own module and upgrade to pac4j

Initial commit
CAS-1286: Extract the OAuth client support in its own module and upgrade to pac4j

Merge with master
CAS-1286: Extract the OAuth client support in its own module and upgrade to pac4j

Generate NOTICE for cas-server-support-pac4j
Merge remote-tracking branch 'upstream/master' into CAS-1286
Merge remote-tracking branch 'upstream/master' into CAS-1286
CAS-1286: Extract the OAuth client support in its own module and upgrade to pac4j

After Misagh's code review
CAS-1286: Extract the OAuth client support in its own module and upgrade to pac4j

Handle properly required additionnal HTTP action from pac4j
Merge pull request #223 from leleuj/CAS-1286

CAS-1286: Extract the OAuth client support in its own module and upgrade to pac4j