Fix a few more rspec deprecations hiding out in the sunspot test suite.

* mock -> double
* raise_error
Remove hanna as a development dependency.

It's long-unmaintained.
Rely on RDoc::Task rather than the defunct Rake::RDocTask
Fix the sunspot and sunspot_rails doc tasks by referencing the proper relative path to the readme file.
Fix the sunspot and sunspot_rails doc task under 1.8.7, primarily to get travis ci green.
Note that rails 4.0 is tested in the sunspot_rails readme.
Add rake to the sunspot gemfile, mainly to satisfy travis ci.

https://travis-ci.org/sunspot/sunspot/jobs/10522726
Use rake db:test:prepare in sunspot_rails test setup.
correct Sunspot.remove! with block test, and get it to pass by propagating block down the call chain.
allow all #remove_by_id(!) to accept (splat or) array of ids, and add testing coverage
Merge branch 'rspec-deprecations'
Merge branch 'rdoc-travis-updates'
Merge branch 'remove_with_block'