tracker_api does not specify activemodel dependency version

[tmertens]

tracker_api raises an exception when used with activemodel versions 3.2.x, which does not define ActiveModel::Model. The gemspec should specify a minimum version of activemodel 4.x.

~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/resources/base.rb:10:in `<module:Base>': uninitialized constant ActiveModel::Model (NameError)
    from ~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/resources/base.rb:7:in `<module:Resources>'
    from ~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/resources/base.rb:6:in `<module:TrackerApi>'
    from ~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/resources/base.rb:5:in `<top (required)>'
    from ~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/resources/story.rb:4:in `<class:Story>'
    from ~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/resources/story.rb:3:in `<module:Resources>'
    from ~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/resources/story.rb:2:in `<module:TrackerApi>'
    from ~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/resources/story.rb:1:in `<top (required)>'
    from ~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/endpoints/story.rb:19:in `get_story'
    from ~/.rvm/gems/ruby-2.1.5@avant_basic/gems/tracker_api-0.2.9/lib/tracker_api/client.rb:140:in `story'

My local activemodel versions:

$ gem list --local activemodel

*** LOCAL GEMS ***

activemodel (3.2.21, 3.2.19)

Workaround

To work around this issue, update activemodel:

gem update activemodel