allow override page url and save_as values directly from the metadata

this is similar to the template override implemented in #404
add functional test for save_as/url override

and update functional tests output
add docs for save_as/url override from metadata feature
Fix typo
Fixing issue #712.

This commit adds documentation to the getting started guide which describes that
articles must contain a manually set 'date' metadata attribute unless the
DEFAULT_DATE setting is specified.

This fixes some incorrect documentation behavior discussed in the ticket.
fix null attributes in html parser
Merge pull request #718 from mankyd/null-attribute

Fix null attributes in new HTML parser
Merge pull request #717 from rdegges/master

Fix issue #712
Merge pull request #713 from vially/patch-1

Fix typo in documentation
Add a pages_generator_finalized signal.

I wrote a plugin that I'd like to also be able to run on pages in
addition to articles. Adding this signal will let me update the content
when a page is finished being generated.
fix string formatting errors
format exceptions as strings
Merge pull request #721 from mankyd/log-error

Fix String Formatting Errors
Merge pull request #719 from streeter/pages_generator_finalized

Add a pages_generator_finalized signal.
support inline summary specification

update documentation

change summary cutoff to a plugin

remove backup file

fix 3.2 tests

update summary plugin initialization and documentation

update documentation

fix documentation formatting
Merge pull request #716 from mankyd/summary-cutoff

Summary Cutoff
Fix Travis image link target in README
PageClass arg is useless in content_object_init
remove hardcoded values for SUMMARY_BEGIN_MARKER and SUMMARY_END_MARKER
update summary plugin so that tests are fixed (hopefully)