cargo build --bin BIN

Command `cargo build --bin BIN` where BIN is space-separated list
of binaries rebuilds only those binaries.

As a side effect, `cargo run --name NAME` now build only binary to
be executed.
auto merge of #843 : stepancheg/cargo/build-bin, r=alexcrichton

Command `cargo build --bin BINS` where bins is space-separated list
of binaries rebuilds only those binaries.

As a side effect, `cargo run --name NAME` now build only binary to
be executed.