Compatibility fixes for Redmine 2.0

[rkallensee]

I made a few quick fixes to get the plugin working on Redmine 2.0. I updated the documentation and while I was at it I added the German translation.

[thimios]

I use Redmine 2.3.3.stable.12240 and the latest code from https://github.com/rkallensee/redmine-google-analytics-plugin

I get a 404 when opening /settings/plugin/google_analytics_plugin

Here is what I see in the redmine log:

Started GET "/settings/plugin/google_analytics_plugin" for 78.52.17.72 at 2013-11-09 13:57:17 +0100
Processing by SettingsController#plugin as HTML
Parameters: {"id"=>"google_analytics_plugin"}
Current user: thimios (id=1)
Rendered settings/plugin.html.erb within layouts/admin (2.4ms)
Missing template, responding with 404
Rendered common/error.html.erb within layouts/base (0.2ms)
Rendered plugins/redmine_code_review/app/views/code_review/_html_header.html.erb (0.0ms)
Rendered plugins/redmine_code_review/app/views/code_review/_body_bottom.html.erb (0.0ms)
Completed 404 Not Found in 31ms (Views: 19.2ms | ActiveRecord: 3.0ms)

any ideas? Thanks!

[timc3]

The template is name incorrectly I think, in app/views/settings it should be _google_analytics_settings.html.erb