[develop] CLI listing plugins fails

[DePierre]

OWTF fails to list any of its plugins as shown below:

tour-depierre owcs/owtf ‹develop› » python2 owtf.py -l web

 _____ _ _ _ _____ _____
|     | | | |_   _|   __|
|  |  | | | | | | |   __|
|_____|_____| |_| |__|

        @owtfp
    http://owtf.org

[*] OWTF Version: 1.0.1, Release: LionHeart (Beta) 
[-] Loading framework please wait..
Traceback (most recent call last):
  File "owtf.py", line 531, in <module>
    main(sys.argv)
  File "owtf.py", line 508, in main
    run_owtf(core, args)
  File "owtf.py", line 472, in run_owtf
    if core.Start(args):
  File "/home/depierre/git-repo/owcs/owtf/framework/core.py", line 282, in Start
    if self.initialise_framework(options):
  File "/home/depierre/git-repo/owcs/owtf/framework/core.py", line 292, in initialise_framework
    self.PluginHandler.ShowPluginList()
AttributeError: Core instance has no attribute 'PluginHandler'

The same goes for net and aux.
@alessandrofg This seems to come from your re-architecture pull request.

[alessandrofg]

I think this should also be failing in the master branch.