Revert removal of "safe" template tag from blog/news headlines.

Conservancy use HTML entities in their titles.

Remove unnecessary use of "safe" template tag.

This tag marks a variable as not requiring escaping by the template engine,
potentially creating cross-site scripting vulnerabilities, so shouldn't be used
unless absolutely necessary. In these cases, I don't think it's necessary.

Blog: typo fix in template.

Template had a typo from last commit.

Blog: add permalink on partial entries.

I noticed there is no link on the blog pages (other than on the front
page) to get the link to the blog post itself. This adds a permalink at
the end near the tags.

I considered making the title itself a link, which is what's done on the
frontpage, but I figured this might look nicer. Feel free to change
this if you're looking this commit message and feel I didn't DTRT
here. :)

blog: Headlines clear floats.

This avoids a situation where multiple summaries have floats that stack on
top of each other vertically, which end up getting far away from the actual
text.

In order to make this work, we had to change the styling of #mainContent on
blog pages (and others with a sidebar). Otherwise, headlines with
class="clear" would clear the sidebar as well.

blog: Refactor entry rendering into a partial.

This helps ensure that entries are rendered consistently wherever they
appear.