Bug Fixes and Filtering

• added theme color styles for pull quote block.
• added image opacity styles for pull quote.
• Fix photo essay caption colors in Editor
• Fix button text color when in <p> tag #209
• Update headline anchor setting #207
• Only call onChange on Background component if it exists as a function #206
• Use post date as pre-formatted in related stories list #205
• Remove unused "Sample" and "Block" blocks #204
• Add Post Type Block Filtering: #199