Fix option naming or add second option to download really all optional files

### Step 1: Please describe your environment

* ZeroNet version: 0.6.2
* Operating system: Win. 10
* Web browser: Firefox
* Tor status: available
* Opened port: yes

ISSUE:

Hello, in [this Zerotalk topic](http://127.0.0.1:43110/Talk.ZeroNetwork.bit/?Topic:1519472222_1L4dZcDF2maSKHDy788yhxpYnBWnXadUtS/How+are+ZeroNet+big+files+distributed+from+one+seeder+to+many+peers) was mentioned that the (0) menu option "Download and help distribute all files" in fact does not downloading all optional files because "big" files are skipped.

PROPOSAL:

A) Change "Download and help distribute all files" to "Download and help distribute all <123MB files"
B) add input field where user can adjust maximum file size to download
C) add second option which will download really all files. User should see disk space needed for all files and disk space needed only for "small" files.