Implement new 1.8 interfaces

[luna-duclos]

Go 1.8 has added a bunch of new interfaces that need to be wrapped, all the context related functions pretty much.

[qustavo]

You're right, great point.

[qustavo]

After reading database/sql implementation, I've realized that:
Query("SELECT * FROM TABLE") calls QueryContext(context.Background(), "SELECT * FROM TABLE"). So effectively, by hooking to the Driver's Query implementation will work for both cases.

[qustavo]

done in #5