SetupFramework: log thread error to console

Because logger.error from a non-main thread is lost.

+ Increase verbosity of virtualenv exception.
+ Introduce LocalExecution.py library.
+ Include multiple other style improvements.
+ Add some ssh.py improvements:
  + Accept also commands of OptionString type.
  + Introduce a limited form of raise_from for exception chaining.
  + Add include_reason argument to exec_cmd_no_error.

Change-Id: I0cd92bcdaa1a5c4cc20cb99067593fc3b40d2c31
Signed-off-by: Vratko Polak <vrpolak@cisco.com>