Building and installing need to be run with different privileges

`make link`:

```
cargo build --release
Finished release [optimized] target(s) in 0.0 secs
ln -s /home/jbrown/ethrun/target/release/ethrun /usr/local/bin/
ln: failed to create symbolic link '/usr/local/bin/ethrun': Permission denied
Makefile:6: recipe for target 'link' failed
make: *** [link] Error 1
```

`sudo make link`

```
make: Entering directory '/home/jbrown/ethrun'
cargo build --release
Unable to update https://github.com/paritytech/parity#33dd4916

To learn more, run the command again with --verbose.
Makefile:5: recipe for target 'all' failed
make: *** [all] Error 101
make: Leaving directory '/home/jbrown/ethrun'
```

I had to run the following command manually:

```
sudo ln -s /home/jbrown/ethrun/target/release/ethrun /usr/local/bin/
```