README: listed all supported types
README: links to standard interfaces
Merge pull request #8 from go-pg/feature/list_all_supported_types_in_readme

List all supported types in README
Remove debug log.
Use driver.Valuer interface.
encoder: Support full range of pointer data types

After dereferencing a pointer, we pass the value to appendIface (which knows about time.Time etc)
instead of appendValue (which doesn't).
Fix setting zero values on NULL

Fixes #7
Changed treatment of timezones: timezoneless values assumed to be in Local TZ