User can share shells/hosts with other users

[sebas5384]

The user can share a shell/host with another user.

User A shares with user B, user B can't modify the shell (read only).

Possible solutions:

1. User A generates a hash and send it to user B. User B imports the hash.
2. User A generates a password protected link and send it to user B. User B access the links address and login with the given password.
3. User A clicks on share of the shell item and mention the B user's name.

[sebas5384]

We could use URI browser schema to share the shell's info

[sebas5384]

this PR is related #9