remove unicode gem dependency

Turns out the unicode normalization functionality from it we were using
has been in ActiveSupport since 3.0. So un-needed, and we can simplify
things substantially without the unicode gem -- which only worked on
MRI anyway, maybe had problems in ruby 2.0, and required alternates on
jruby etc. Much simpler now, just use ActiveSupport!
Merge pull request #632 from jrochkind/remove_unicode_gem

remove unicode gem dependency
added newline so a Mime::Type doesn't get appended to a comment
SolrDocument ids are strings, not fixnums. Fixes #636
Merge pull request #637 from projectblacklight/issue_636

SolrDocument ids are strings, not fixnums. Fixes #636
Merge pull request #635 from bmaddy/issue-633

added newline so a Mime::Type doesn't get appended to a comment
render search results header content (did you mean, constraints, sort and per page tools, etc) in a separate, overridable partial
Merge pull request #639 from projectblacklight/search-header-partial

render search results header content (did you mean, constraints, sort an...