v2.0.0

Changes:

1. Connection URL parsing implemented.
2. Pool and Conn constructors now takes Into<Opts> (implemented for &str).
3. Everything was reexported to top level.
4. Few new structs added:
   • Row - to replace raw Vec<Value>
   • MySqlError - to replace reexported ErrPacket
   • Params - to replace raw Vec<Value>. This is for upcoming #31 fix.
5. IntoValue removed in favor of Into<Value>
6. ToRow removed in favor of Into<Params>
7. SignedDuration removed in favor of time crate's Duration
8. Bunch of renames:
   • Rename Opts.tcp_addr -> Opts.ip_or_hostname
   • Rename MyConn -> Conn
   • Rename MyPool -> Pool
   • Rename MyPooledConn -> PooledConn
   • Rename MyError -> Error
   • Rename MyIoError -> IoError
   • Rename MyDriverError -> DriverError
   • Rename MySslError -> SslError
   • Rename MyResult -> Result