automate ODLPARENT-219 (losing karaf shell on feature:install)

this is a user facing annoyance that would be nice to protect against regressions. the
test steps are easy and ODL CSIT infra should have all the bits and pieces to do this
in a robot job. simple steps:

1. ./bin/start
2. ./bin/client
3. feature:install <whatever>

then just validate

1. interaction with the karaf shell. (e.g., feature:list)
2. logout of shell and back in with ./bin/client
3. repeat some interaction