(maint) Signal a PCP error during Association as error
(maint) Signal a PCP error during Association as error

In case the PCP Error message received during a Session Association is
releated to the Associate request, the Connector::connect will now raise
a connection_association_error, as documented, instead of wrongly raise
a connection_response_failure.

puppetlabs/cpp-pcp-client,puppetlabs/cpp-pcp-client,MikaelSmith/cpp-pcp-client,MikaelSmith/cpp-pcp-client,MikaelSmith/cpp-pcp-client,MikaelSmith/cpp-pcp-client,MikaelSmith/cpp-pcp-client,puppetlabs/cpp-pcp-client,puppetlabs/cpp-pcp-client