Update vedeu to 0.1.17 to fix crash

Fixes crash with 0.1.16:

```
$ playa
$HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/vedeu-0.1.16/lib/vedeu/support/groups.rb:48:in `block in in_memory': uninitialized constant Vedeu::Groups::Set (NameError)
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/vedeu-0.1.16/lib/vedeu/support/groups.rb:27:in `yield'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/vedeu-0.1.16/lib/vedeu/support/groups.rb:27:in `add'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/vedeu-0.1.16/lib/vedeu/support/buffers.rb:11:in `create'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/vedeu-0.1.16/lib/vedeu/api/interface.rb:22:in `define'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/vedeu-0.1.16/lib/vedeu/api/interface.rb:10:in `define'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/vedeu-0.1.16/lib/vedeu/api/api.rb:87:in `interface'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/playa-0.0.13/lib/playa/application.rb:5:in `<class:Application>'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/playa-0.0.13/lib/playa/application.rb:2:in `<module:Playa>'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/playa-0.0.13/lib/playa/application.rb:1:in `<top (required)>'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:53:in `require'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:53:in `require'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/playa-0.0.13/lib/playa.rb:19:in `<top (required)>'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:53:in `require'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:53:in `require'
	from $HOME/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/playa-0.0.13/bin/playa:9:in `<top (required)>'
	from $HOME/.rbenv/versions/2.0.0-p353/bin/playa:23:in `load'
	from $HOME/.rbenv/versions/2.0.0-p353/bin/playa:23:in `<main>'
```