search[post_id] for artist commentary
should fix #2320

Sources::Site#normalize_for_artist_finder! catches errors that occur
during the normalization process. However it only catches
StandardErrors, not Exceptions, so this makes Sources::Error a
StandardError.
Don't make pixiv http requests when displaying artist history

The reason the urls need to be normalized at all here is because legacy
urls from Danbooru 1 don't have their unnormalized counterparts stored
anywhere and thus can't be accurately compared with unnormalized urls
from Danbooru 2.
Automatically remove dupe urls

fix #2321
Display more detailed error, only if it exists
#2321: Fix for 3+ dupes too
allow gift upgrades for accounts
fix user secondary links
new version
update rails version
Merge branch 'ruby-2.1'

This reverts commit 616aef439496044861840fff546bb2306ce19c46.
fix warnings
compatibility fixes
fix Pixiv#get_image_url_from_page
Fix regression with pixiv manga uploads
fix for Pixiv#get_image_url_from_page
fixes #2325
fixes #2326
#2326 fix has_mail being set by wrong copy
fix error