Ignore None's values when using the ItemLoader.
Unused re import and PEP8 minor edits.
Expose current crawler in the scrapy shell.
PEP8 minor edits.
RegexLinkExtractor: encode URL unicode value when creating Links
Updated shell docs with the crawler reference and fixed the actual shell output.

Also updated the shell example with a reproducible code example.
Updated the tutorial crawl output with latest output.
Merge pull request #561 from redapple/regexlx-encoding

RegexLinkExtractor: encode URL unicode value when creating Links
Merge pull request #556 from darkrho/item-loader-nones

Make `ItemLoader` ignore `None` values from processors.
replace unencodeable codepoints with html entities. fixes #562 and #285
Merge pull request #557 from darkrho/expose-crawler-in-shell

Expose current crawler in the scrapy shell.
Merge pull request #565 from dangra/562-sgmlinkextractor

replace unencodeable codepoints with html entities
Merge remote-tracking branch 'origin/master' into lxmlextractor
Support rel="nofollow" links attribute and add tests for it