Update formatNamedParameters to not match parameters starting with digit

Using a query like:
query = "SELECT * FROM t WHERE create_at > CURRENT_DATE + CURRENT_TIME - time '01:30' LIMIT :limit";
Sequelize.query(query, null, {raw: true}, { limit: limit })
will fail due to "time '01:30'" where it will look for a parameter named '30'
added a test
updated the test for postgres
Merge pull request #1086 from triptec/master

Update formatNamedParameters to not match parameters starting with digit