Fix #1015 change nav bar blog link "Impressions"

Have also changed the slug to 'impressions', which may require the
category to be created/renamed.
Fix #1014 change homepage location search box text

From "Location name" to "Enter your location"
Fix #1013 swap survey and twitter on homepage
Merge branch 'issues/1013-homepage-swap-twitter-and-survey'
Merge branch 'issues/1014-location-search-box-text-homepage'
Merge branch 'issues/1015-change-nav-bar-blog-link'