Setting max size for event images on main screen and detail screen

Fixes https://www.pivotaltracker.com/story/show/80069244
Adjusting spacing for Subkast headers

Fixes https://www.pivotaltracker.com/story/show/77306458
Replacing Instagram with Tumblr, also fixing blog links

Fixes https://www.pivotaltracker.com/story/show/79953662
Allowing description to overflow, removing scrollbars. Also, allowing words to break.

Fixes https://www.pivotaltracker.com/story/show/75095452 and https://www.pivotaltracker.com/story/show/69913722
Newsletter sign-up notice
Increasing contrast for comment 'Reply' option
Sidebar adjustments
Minor sidebar and style fixes
Centering logo elements so everything aligns properly
Merge branch 'NewsletterSignup' of github.com:mcongrove/kiwi into UIAdjustments

Conflicts:
	app/assets/stylesheets/application.css.scss
Header adjustments for logged-in state and for other screens
Fixing misaligned upvote counts
Merge branch 'SubkastHeader' of github.com:mcongrove/kiwi into UIAdjustments

Conflicts:
	app/assets/stylesheets/application.css.scss
Trying lowercase "am" and "pm"
Merge branch 'ReplyButtonContrast' of github.com:mcongrove/kiwi into UIAdjustments

Conflicts:
	app/assets/stylesheets/application.css.scss
Merge branch 'ReplyButtonContrast' of github.com:mcongrove/kiwi into UIAdjustments
Merge branch 'AboutFaqFixes' of github.com:mcongrove/kiwi into UIAdjustments
Merge branch 'DescriptionOverlay' of github.com:mcongrove/kiwi into UIAdjustments

Conflicts:
	app/assets/stylesheets/application.css.scss
Merge branch 'MaxImageSize' of github.com:mcongrove/kiwi into UIAdjustments

Conflicts:
	app/assets/stylesheets/application.css.scss
Header, and user drop-down menu fixes