altered CSS to more closely match github's markdown css.

Main chaings:
Padding between LIs = 0px
Fixed page-width: 920px
H1, H2, H3: Margin-top: 20px; margin-bottom: 10px
Merge pull request #597 from shanebdavis/master

altered CSS to more closely match github's markdown css
Update gollum.gemspec
Add test for #602
Update test #602
Fix #602
Release 2.4.5
Update 1.8 check
Fix /pages css to the correct path for images
Merge pull request #605 from dekimsey/pages-images-now-respect-baseurl

Fix /pages css to the correct path for images
Fix #607
Update
Fix #607
ASCIIDOC tests don't run on Travis

Tests that use to be green now fail when rerun. The issue is with the travis configuration and asciidoc.

https://travis-ci.org/github/gollum/jobs/3603171
Release 2.4.6
Fix #491
More work on #491

@teohm pointed out that add_to_index in gollum/committer.rb already appends @wiki.page_file_dir
Fix spaces in dir #611
Fix #611
Fix tests

File names do not have spaces.