Allow shell quoting on CLI

Break up command-line args using shlex rather than string.split

This enables multiple-word tags using quotes:

mailpile> tag/add "three word tag"
mailpile> tag +"three word tag" 20
removed unused import of Unix-only module 'fcntl' from mailpile/crypto/streamer.py
removed unused import of Unix-only module 'fcntl' from mailpile/crypto/symencrypt.py
Unix-only module 'fcntl' is now imported within GnuPG.run within try-except-ImportError to make this module importable under Windows, to allow Windows-developer reimplement GnuPG.run with althouth-Windows modules
import of Unix-only module 'readline' now within try-except-ImportError to make this module importable under Windows
added 'markupsafe' and 'nose' to the required third party packages, but without version number
Handle more weird errors without asploding
Added translatable tag names for built-in tags.
Make reading mail on the CLI work again
Improved CLI search results, made CLI message threads navigable
Fixed broken URL mangler, made less easily frightened
Added attachment_type jinja extension for #654
Made composer show up in Reply thread, even if already replied to a message
Updated font icon set with a bunch of new cool icons
Made Sidebar allow for custom icons as specified in tag.icon
Updated compiled CSS... we really should make this not included in repo
Test script for message header parsing work
Merge pull request #661 from mattcarberry/translatable-builtins

Added translatable tag names for built-in tags.
Merge pull request #606 from dlmueller/master

Make mailpile importable under Windows
Added crypto_policy command.

- New crypto_policy command for a single user
- New discover_crypto_policy to discover policy to existing vcards
- new crypto_policy/set command to change policy for an email
- Added gpg dependency to travis
- Added test keys to keyring, one signed and one encrypted mail
- Policy is not yet considered in compose