Replace CivetStudy with CivetVirtualStudy about cbrain-plugins-neuro

[prioux]

Sample code for usage of the class, from the programmer's perspective. Can be used in the console.

• Creating it

# Properties of the file, to adjust
dp_id = 23; name = "virtcivet"; user_id = 1; group_id = 1;
co_ids = [23,45] # ID of some CivetOutputs

# Create it
uf = CivetVirtualCollection.new(:name => name, :dp_id => dp_id, :user_id => user_id, :group_id => group_id) # hope I got them all
uf.save!

# Set content
uf.cache_prepare
path = uf.cache_full_path
File.mkdir(path.to_s)
uf.set_civet_outputs(CivetOutput.find(co_id), current_user) # need current_user for validation
uf.sync_to_provider

• Use an existing CivetVirtualStudy, from any Remote Resource

# Prep; adjust in console
cs_id = 234; # id of the study

# Find it
cs = CivetVirtualStudy.find(cs_id)
cs.sync_to_cache
cos = cs.get_civetoutputs(current_user) # returns array of CivetOutput objects

# Do something with content of each CivetOutput
path = cs.cache_full_path
Dir.chdir(path.to_s) do 
  cos.map(&:name).each do |co_name|
    system("ls -ld #{co_name.bash_escape};du -D -h #{co_name.bash_escape}")
  end
end

The current_user is needed in some methods to be passed to validation code of CbrainFileList methods.