Fix ip binary not being found on some flavors of Linux

[GitSquared]

Pull Request

This is a fix for an issue reported downstream at GitSquared/edex-ui#227

Changes proposed:

• Fix
• Enhancement
• Remove
• Update

Description (what is this PR about)

Following this issue that I reported back in March, support was added for using ip instead of ifconfig to detect network interfaces on Linux (9d13697, shipped in v3.37.5).

However, on some distros, ip isn't located at /sbin, and because of this the library tries to use ifconfig instead, which fails because most of these bleeding-edge systems don't have it available.

This PR replaces the /sbin/ip file-exists check by a command -v one that will succeed if ip is available in $PATH.

[sebhildebrandt]

@GitSquared : Thank you for your pull request. I made a little investigation and now tried to modified it to use the which command ... should also work. Generally the function getMacAddresses() was introduced to a problem in node 7.10 to 8.1 (uv_interface_address - nodejs/node#13581). So as this should no longer be a problem, I have to think, how long I will keep this workaround in place ;-)

So I just released a fix for this v3.50.2 ... can you test it on your side?

[GitSquared]

@sebhildebrandt Nice one using which. This works on my side, I'm gonna pull the update downstream.

And uh, sorry for the spike in downloads.