Using connection pools

Right now we're using DriverManagerDataSource which creates a new connection every time someone accesses it. We need to move to C3P0 connection pool instead to get performance benefits. Refer to how it's implemented in Poulpe for a quick overview.
After applying a connection pool, we need to configure it approximately. Since we have 30-35 threads by default from Tomcat, let's configure the pool for 35 connections max.
This task should be tackled after performance tests are written