Try uiautomator
from command line to find out if it's there or not:
$ adb shell uiautomator
if your output is similar to
Usage: uiautomator <subcommand> [options]
Available subcommands:
help: displays help message
...
then you have uiautomator
installed. Otherwise if the output is
/system/bin/sh: uiautomator: not found
then you forgot to include it in the image.
You don't need ViewServer if UiAutomator is used as AndroidViewClient back-end.