tests/functional: remove unused `json` import
zvsh: reimplement is_binary_string for py3 compat
zvsh: python3 fixes
tests/functional: python3 fixes
Merge pull request #46 from larsbutler/functional-tests

Functional tests
Ignore backup files
tests: avoid encoding literals

We only support Python 2.6 and later. There the b'...' syntax can be
used instead of doing a dummy encoding:

  https://docs.python.org/2/whatsnew/2.6.html#pep-3112-byte-literals
Merge pull request #47 from mgeisler/small-fixes

Small fixes
fixed ReadError when opening tar files

when using `--zvm-image=....,/,wo` tarfile.ReadError was raised
`zvshlib` tired to search for executable binary in all tar files
fixes issue #48
Merge pull request #49 from pkit/bug_fix

fixed ReadError when opening tar files
use image path only once in manifest file

image path for each image should appear only once in the manifest file
even if `zvsh` was provided with multiple `--zvm-image=` options for the same file
fixes issue #50
better handle multiple fstab entries

`nvram_fstab` was using `dict()` which does not provide mutiple entries for the same device
it's needed when the same file is mounted with different mount points or access flags
Merge pull request #51 from pkit/bug_fix

use image path only once in manifest file
added functional tests for zvm-image args

added more func tests for various `--zvm-image` arguments