Adds a test for circular structures.

acts_as_tree does not check for circular structures in the models it is
invoked on.
Adds validation concerning circular structures.

Infinite tree fetching no more.
Update CHANGELOG.rdoc
Merge pull request #171 from opf/fix/circular-structures

Adds a test and validations for circular structures.
[OPF #907] special version instead of sha1

on admin info page

- moved ChiliProject::Info in OpenProject namespace
updated core special version
[OPF #713] fixes issues description layout

- remove inheritance of font defined in reset.css
- the whole site was affected by this rule, not only the issue
  description
Fixed ambigious cucumber match of login steps
Changed "click on" step to only click on visible elements to prevent
ambigious capybara matches
Removed call to non-existent function formerly removing a line from
a table as the following modify of an existing attribute with the
already-existing line from the table should not cause problems as
long as it is not a key attribute
Merge pull request #178 from opf/feature/rails3_fix_reset_css

[OPF #713] fixes issues description layout
Merge pull request #177 from opf/feature/rails3_show_full_version_in_admin_info

[OPF #907] special version instead of sha1 on admin info page
Added check to not add already existing trackers in case some previous setup
step already added the same tracker
Cucumber: Take screenshot & save HTML when a scenario fails

Screenshots are stored in <rails root>/tmp/capybara
Merge pull request #180 from opf/feature/rails3_cucumber_screenshots

Cucumber: Take screenshot & save HTML when a scenario fails
Merge pull request #179 from opf/feature/rails3_fix_reporting_cukes

[OPF #764,765] Feature/rails3 fix reporting cukes