Add fallback for jrpc client connection when failing to connect.

[BryanDClark]

The ADB proxy server may be listening on 127.0.0.1 on machines where localhost resolves to [::1], which will raise a 'ConnectionRefusedError'.

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[xpconanfan]

Looks like CI is broken. Please fix the test.

[BryanDClark]

Hm...looks like one of the checks failed because 'ConnectionRefusedError' doesn't exist in python2. Should I switch this to catch all exceptions so it's python2 compatible?

[xpconanfan]

What error does it throw in py2?

[BryanDClark]

socket.error, I believe: https://docs.python.org/2/library/socket.html#socket.error

[BryanDClark]

I updated the except statement to catch exceptions based on the python version, seems to work for python3 (I'll let the presubmit check for python2)

[xpconanfan]

Could you add a TODO to use a more specific error type after PY2 is deprecated from this code base?

[BryanDClark]

Added a TODO