Fix range! docs
Fix double borrow of conn RefCell<T>
Merge pull request #61 from mikedilger/fix_double_borrow

Fix double borrow of conn RefCell<T>
Detect direct queries to COPY FROM
Initial COPY FROM support!

cc #51
Don't flush more than needed when copying
Correctly handle bad column counts in copy
Remove Binary/Text choice from ToSql

Text format doesn't work with our COPY implementation, and FromSql is
already binary only.
Add prepare_copy_in to transaction
Add some prepare_copy_in docs
Remove some unused methods
More docs + return copy count from execute
Add column_types to copy in statement
Move from the deprecated liburl to servo/rust-url