this part of the exception suggests that hibernate tries to create connection itself:
Caused by: java.sql.SQLException: No suitable driver found for jdbc:mysql://10.21.101.175:3306/jbpm5
at java.sql.DriverManager.getConnection(Unknown Source) [rt.jar:1.6.0_32]
at java.sql.DriverManager.getConnection(Unknown Source) [rt.jar:1.6.0_32]
could you please attach all persistecne related config files?
HTH