A few PEP8, spacing and spelling fixes
Merge pull request #35 from izderadicka/master

Several small fixes

Fixes #11
Merge branch 'master' of github.com:OpenXenManager/openxenmanager
Just spacing
Strorage can be also created from host screen -   in that case code
throws exception in part where vdi was to be attached to vm.  This
change assures that reference is there only if VM is selected.
Some spacing fixes plus
there was tricky error when pushing alerts to window
it used lambda closure do do the job, however closure also referenced 
some fields in the object itself.  Since this closure was pushed to GTK
event loop it was executed later asynchronously and state of object
could change -   thus we can see diffrent KeyError exceptions, because
closure was evaluated against diffrent object state then expected.