Integrity checker should not check for "odd number of #" in url field

[Siedlerchr]

Jabref 3.4, Windows 7x64

Enter the following entry and then run the integrity check:
You get
url | odd number of unescaped '#'
However, biber etc handle the url field as verbatim, when the reference is printed

@WWW{scikit-learndevelopers2010a,
  author    = {scikit-learn developers},
  title     = {Ensemble methods},
  date      = {2010/2014},
  url       = {http://scikit-learn.org/stable/modules/ensemble.html#random-forests},
}

[matthiasgeiger]

refs #1188 and #1217

[lenhard]

Fixed by #1567