dropping the rails directory

this was only needed for Rails 2, which we don't support any more.
Take ownersship into account when exclude: true

fixes #341
Remove dead code

thank you @medihack
fixes #115
move related_tag specs to their own file
add specs for related tags on custom context

fixes #263
modernize  old-style spec_helper includes

just use require 'spec_helper' now
upgrade ammeter dep
Reduce number of queries for acts_as_ordered_taggable
Merge pull request #355 from rsamoilov/optimize_acts_as_ordered_taggable

Optimize acts_as_ordered_taggable
refactor STI specs into one file

Squashed commit of the following:

commit 61552514322dbd725a34cfec62f94d2a3b72f3bb
Author: Joost Baaij <joost@spacebabies.nl>
Date:   Wed Apr 24 22:41:09 2013 +0200

    STI specs: ownership

commit d4f493ecae9a73693ee39bdbda41232bd637a793
Author: Joost Baaij <joost@spacebabies.nl>
Date:   Wed Apr 24 22:37:38 2013 +0200

    STI specs: related tags and tag list

commit dc84ec8b2c73b6e0f061ab199cb2c6460205de8c
Author: Joost Baaij <joost@spacebabies.nl>
Date:   Wed Apr 24 22:20:40 2013 +0200

    STI specs: extract matching contexts vars

commit 2095bea6f15fd775186a348c3ac20b29d3c79f5a
Author: Joost Baaij <joost@spacebabies.nl>
Date:   Wed Apr 24 22:09:32 2013 +0200

    STI specs: extract context vars

commit b02bd7e37bd153528e0fe37cc8530fb052ae192d
Author: Joost Baaij <joost@spacebabies.nl>
Date:   Wed Apr 24 22:03:32 2013 +0200

    Pull out STI specs into a separate file

    Need to investigate #220 and the specs are just a mess.
introduce classnames for the mocks that are easier to understand

TaggableUser -> User
InheritedTaggableUser -> Student

ahhh. much better.
add testcase for STI tag ownership

the testcase was green right away, so this was working properly.
but it doesn't hurt to fix every method, does it?

fix #220