Fix broken BrowserStackLocal binary after first test

[Krinkle]

Currently after installing browserstack-runner you can run one test.
After that, the command is broken. There are numerous symptoms
from this:

• BrowserStackLocal gets re-downloaded every single time.
• an ETXTBSY error appears because the previous file is still busy.

Here is what happens on later runs:

• fs.exists(localBinary) finds the binary.
• runTunnelCmd(['-version']) gets the following output:

$ node_modules/browserstack-runner/lib/BrowserStackLocal -version
Sun Apr 11 2021 20:59:41 GMT+0000 (UTC) -- BrowserStackLocal v8.1

Sun Apr 11 2021 20:59:41 GMT+0000 (UTC) -- Container runtime environment detected
Sun Apr 11 2021 20:59:41 GMT+0000 (UTC) -- Attaching services to public interface
BrowserStack Local version 8.1

• Only the first line of data is checked by subProcess.stdout.on('data').
• The line does not match /version\s+(\d)/. It reports: Tunnel binary: found version null.
• The script invokes callbackOnce() and will try to kill the process. This may succeed, but it is not immediate as there are additional output lines still in the data buffer which must be processed first, which is not possible since we are still indirectly in the call stack of the first data stdout callback.
• The re-download begins, but the operating system does not permit writing to a currently executing binary, since it will not shutdown until a few milliseconds later.
• We fail with Error: ETXTBSY: text file is busy.

All of this happens only because -version is interpreted as both -v for verbose and --version at the same time, the verbose output comes first and does not match the regex. Changing it to --version solves the problem.

This code should also be changed so that it actually waits for this subprocess to exit. Perhaps falling back to unlinking the file if we can't close it so that at least the redownload will work. But, that is another issue and will not be a problem in most cases.

Fixes #224.