KPL Binary installation uses a Shared Lock

[skidder]

The KPL binary is vulnerable to a race condition that yields a zero-byte binary file being installed. The sequence is:

1. Process-1 determines that the binary does not exist and creates a new FileOutputStream, which will create a file-descriptor on the filesystem (link)
2. Process-2 determines that the file exists and creates a FileInputStream and shared lock: (link)
3. Process-1 attempts to create an exclusive lock but cannot because Process-2 has a shared-lock that prevents the creation of exclusive locks: (link)
4. Process-2 verifies the contents of the binary and throws a SecurityException because the contents do not match the expected value: (link)

This can be avoided by using a dedicated lock-file separate from the binary file being written.

This issue is related to #55

[pfifer]

Thanks for reporting this, and providing the PR.