Make pyflakes and pep8 happy
Refactor and update test to pass on gtk 3.8 using nosetests
Mark some code as not to be covered with tests
Derive all classes from object explicitely

This fixes annoying warnings like:
/usr/lib64/python2.7/site-packages/gi/types.py:226: RuntimeWarning: Mixin class dogtail.tree.Application is an old style class, please update this to derive from "object".
  RuntimeWarning
Fix for failing 'focus.application.node' seting

Test failure:
Traceback (most recent call last):
File "/home/travis/build/roignac/dogtail/tests/gtkdemotest.py", line 15, in setUp
  self.pid = dogtail.utils.run('gtk3-demo')
File "/home/travis/build/roignac/dogtail/dogtail/utils.py", line 118, in run
  focus.application.node = child
File "/home/travis/build/roignac/dogtail/dogtail/procedural.py", line 57, in __setattr__
  self.__class__.__dict__[name] = value
TypeError: 'dictproxy' object does not support item assignment
Fix for test_predicates_generic_by_label: generate a better script method call for labels

Fixes the following exception:
Traceback (most recent call last):
File "/home/travis/build/roignac/dogtail/tests/test_predicate.py", line 160, in test_predicates_generic_by_label
  False), u'child(label="dummy name 1", recursive=False)')
  AssertionError: u'child(label=\'"dummy name 1"\', recursive=False)' != u'child(label="dummy name 1", recursive=False)'
  - child(label='"dummy name 1"', recursive=False)
 ? - -
 + child(label="dummy name 1", recursive=False)
Trap GErrors in findAllDescendants and retry if it occurs

This fixes crashes in findChildren if elements are being added/removed quickly:
GError: Method "Get" with signature "ss" on interface "org.freedesktop.DBus.Properties" could not be processed as object /org/a11y/atspi/accessible/2310 does not exist
Fixed an bug in sniff discovered by jmolet that made sniff crash when
run from /bin/sniff not /usr/bin/sniff
Added a direct lambda support in the findChildren method, that allows
using non-predicate lambdas to create search properties. These can be
all pure dogtail Node properties (i.e. showing), not limiting to just
pyatspi ones as is when using Predicate. This is code modified from
patch originally submitted by Vadim Rutkovsky (#33), so are the unittests.

More changes to better the find* and Predicate functionality will follow (of
course with regards to backward compatibility).
Extended the default TypingDelay from 0.075 to 0.1 seconds (helps working with certain high unicode charactes, such as 中国互联网络...)
With GTK3.10+ Gdk changes, needed to tune the keyNameToKeyCode function
so that it provides valid keySym in as many cases possible - with both
pre-GTK3.10 as well as GTK3.11+ having the same behavior in typeText and
pressKey.
adding in changes from original code