drop support of macOS 10.5 and earlier

[Youw]

IOHIDDeviceGetService is available since macOS 10.6
dropping an old workaround makes the implementation simpler

Similar to #39.

Fixes #119
Closes #120

[Youw]

Any votes against?

[z3ntu]

I'm fine personally with 10.6.8+ being supported. But there are definitely still people with macOS versions lower than 10.6 that are interested in software on those devices (see e.g. https://github.com/mistydemeo/tigerbrew - this is not just PPC but now everything < 10.9 or something because homebrew dropped support for macOS versions lower than that)

[Youw]

In this particular example, tigerbrew Formula is still using signal11's copy of the repo: (current master) https://github.com/mistydemeo/tigerbrew/blob/4cce1912cc68a15a0d47f5744b489ae68dfe94fa/Library/Formula/hidapi.rb

[Youw]

Maybe it is time, to finally fire a new release, and it will be a last release, that supports macOS 10.5.

[todbot]

I'm fine with this PR. MacOS USB & HID pre-10.6 always had weirdnesses and new macos adoption rate is typically very high among its users.

If we're talking new releases (yay), I like to lobby for #125 being included.

[mcuee]

Good to update and merge this one if it has not been merged.

[mcuee]

@Youw Please merge this as well. Thanks.