Bump rspec to ~> 2.12.0 in test_app

Otherwise, on a fresh rvm install the test_app pulls in rspec 2.0.1
which fails with "undefined method `run_all' for []:Array" when
running tests in the test_app with ruby 1.9.3.
Fix #529 by re-adding html.no-js selector.
Merge pull request #527 from steffengodskesen/bump_rspec_to_2_12_in_test_app

Bump rspec to ~> 2.12.0 in test_app
tweak controller instance-level config to be a deep copy of the class-level config.
bump travis settings
enable travis notifications
Add travis build status icon
Update link to bug/issue tracker :ant:
Add and cleanup tests for search result pagination
fix #528; when per_page or sort values are changed, we should always reset the :page parameter to 1
fix add_solr_field when the first argument is a symbol. first= isn't a thing.
fix #522, make it possible to add custom field accessors that extend
existing field types

e.g.:

Blacklight::Configuration.define_field_access :home_facet_field

---

configure_blacklight do |config|
  config.add_home_facet_field :special_facet_field
end

---

blacklight_config.home_facet_fields
add Blacklight::Catalog#blacklight_solr accessor to the RSolr connection

This should allow e.g. different solr indexes for different controllers,
and gives a place for different rsolr connections to be used based on
query parameters.
taking a stab at supporting something like #523
Merge pull request #532 from projectblacklight/issue-523

Update index_field and document_show_field (and similar) methods to support an optional 'document' argument, which may be used downstream to inject alternative index/show fields based on characteristics of a document.
remove Mash, but leave a deprecated stub for backwards compatbility
BL 4.x is Rails 3.2+, so no need to check for older versions in the spec
rails 4 doesn't generate public/index.html
use specific request methods instead of 'match' (which is removed from Rails 4)
Remove compass from testing environment