Fix inferred name of `src/main.rs`

The crate name should be the package name, not `main`.

Closes #207
auto merge of #208 : alexcrichton/cargo/fix-main-name, r=wycats

The crate name should be the package name, not `main`.

Closes #207
Use indexing instead of get() function to access Vec
Use String::from_utf8_lossy instead of str::from_utf8_lossy