Fixed cargo setup

[mmerfort]

I have moved some files around to make it usable as a library in other programs with cargo.

[kud1ing]

I don't yet understand why this necessary. Does it fix #88 ?

[mmerfort]

Without those changes I could not use rustsqlite as a library:
The library file was “target/deps/liblib-b47d76b0-0.0.rlib” instead of “target/deps/libsqlite3-c8b486a3-0.0.rlib”. This way I could not include the lib with “extern crate sqlite3;” because it was not found.

Here is the Cargo.toml I used to test this: https://gist.github.com/mmerfort/d14863316f780a30094b

[kud1ing]

Ok, i'll merge it then. I was surprised, because the current directroy layout is what the old Cargo suggested.

[kud1ing]

Thanks.