v0.1.3

Changelog:

• perf(caps): use binary search to implement Cap.probe_supported()
• refactor(caps): check for unknown capabilities supported by the kernel
• meta: remove tests directory from distribution
• meta: lower requirement to Python 3.6 (contributed by @martijnthe)
• refactor: tell ctypes about syscall argument types properly
• refactor(misc): use os.fsencode()/os.fsdecode() for process names
• docs: tweak note about python-prctl's behavior
• test: add more tests