fix(PostgreSQL): some queries failed depending on parameter values (#741)

when a NATIVE SQL query (we have very few in the runtime) is passed parameters
of type String when the column is of type BIGINT, for instance,
the query execution fails on PostgreSQL.

As the value type cannot be inferred by the Engine, the fix is to ensure
that the rest API calls the engine passing those numeric parameters as long, and not as String.

Closes [RUNTIME-271](https://bonitasoft.atlassian.net/browse/RUNTIME-271)