Integration

## Context 
We needed to log statistics of all jdbc queries.

## Description
- Complete the `.gitignore` file to filter log files
- In `*Spy` classes, each call to `System.currentTimeMillis()` is replaced by a call to `TimeSource.getTime()`
- Add new features to `JdbcManager` :
    * manage a set of connection factories (implementations of the `ConnectionFactory` interface)
    * manage a set of listeners (implementations of the `ConnectionPoolListener` interface) receiving events from the `ConnectionPool`