Ability to work on multiple files on journal on Dextrose

[anurag_seeta]

Issue:-whenever we save and activity data or have any data stored in the journal and we want to do some data accessing in bulk from the journal then it is not possible i.e. you have to operate on files singularly.

To reproduce the bug
1. open journal
2. Plugin any external storage device and try to copy multiple files at a time into your device from the journal.
3. You won't be able to do that and you will need to copy all the files one by one.

Resolution:-An option for marking several files and operating on them together should be there.

[bernie]

This is a very large UI change. Please, coordinate with alsroot (the Journal maintainer) for implementation details.

[alsroot]

anurag_seeta: It sound like a useful feature but it is overkill for one ticket, please follow Feature request procedure  http://wiki.sugarlabs.org/go/Features/Policy.

[sascha_silbe]

Dupe of #176.