Explicitly check if an object is a class is pydispatch.

* This is to fix a disagreement in between CPython and PyPy.
* https://gist.github.com/4220533
PEP8 on pydispatch/robustapply.py
from_crawler added to spiders
added ftp handler
fix a possible error in contracts post hook
command with multiple crawlers, fix check command
disable logging for scrapy check
allow passing arguments to tox

e.g. "tox -- scrapy.tests.test_contrib_loader" runs test_contrib_loader for Python 2.6 and 2.7
use tox deps instead of "manual" pip install; add lucid and precise environments to tox.ini
add django to test requirements and fix test_djangoitem for modern django versions
make tox test running more consistent with bin/runtests.sh script
reuse runtests.sh and runtests.bat scripts in tox.ini
allow passing arguments to runtests script via tox
use lxml parser with recover option to parse invalid sitemaps. closes #347

thanks chrissboo for reporting the issue and proposing a fix.
Merge branch 'gh-347'. thanks @chrisboo
Merge pull request #329 from kalessin/ftphandler

added ftp handler
Twisted pre 10.2 (lucid) can not setup the required ftp server for tests
Merge pull request #341 from kmike/test-running

Improved tox test running & fixed django tests
Updated documentation of spider arguments to include required super call.
Fixed ordering of super argument call.