Add possibility to pass prefix before cli command

In some case cli command should be called with prefix, e.g. for set
some environment variables like this `env LC_ALL=en_US.UTF-8`. Now
CLIClient has optional argument in constructor - prefix, which will
applying before each call

Change-Id: I1ce5fb322bd75a5499666e184b68ea6e26835a55
2 files changed