First stab at getting charts working with Redmine 2.3

* README.rdoc: Updated installation instructions.  NOTE: Kept original
  project URL for github.

* app/controllers/version_burndown_charts_controller.rb: Use relative
  plugin_assets URL for the construction of the flash embedded object
  HTML. Make create_graph private as this is not intended to be used
  as an action.

* app/views/version_burndown_charts/index.html.erb: Use relative
  plugin_assets URL to obtain the flash chart javascript.

* config/routes.rb: Create routes for the index and get_graph_data
  actions.

* init.rb: Version increment, and register the open_flash_charts
  plugin so that Redmine copies its assets into place.
Correct templates in internationalization strings.

* app/views/version_burndown_charts/index.html.erb: Add space before
  counts.

* config/locales/en.yml:
* config/locales/ja.yml:
* config/locales/no.yml: Update template syntax.
Change Y axis label to "Hours"

* config/locales/en.yml: Change Y axis label to "Hours" from "Hour"