Styles/markup changes as part of breakout and review

Styles/markup changes as part of breakout and review

- Top-nav Drop-left arrows on top of dropdown moved into the right
  place, adjusted code that applies columns to dropdowns with 4+
  items
- GLM Associate Events styles
- GLM Associate Members styles
- Color fixes, remnants of base theme
- Fixed a 500 error
- Slideshow responsiveness fix
- Blocks/Events responsiveness fix
- Navigation styles edited for active, hover, and combinations
- Disabled 3rd level nav dropdown
- Linked Developers in footer
- Fixed off-canvas styles, added client info to off-canvas
- Fixed header image display on interior pages
- Added max-height and max-width to block images
- Blog styles
- Looked into social icon links, but could only find Facebook and
  Youtube with certainty