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
Added translatable tag names for built-in tags.
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
crypto-policy: Changes after review

- Fixed gnupg package name
- Added sign-encrypt policy
- Removed dead passphrase code
Updating result count to match new crypto-policy tests.
Fixing nose tests with new data & clamping test port range a bit more.
 Enhanced plugin loading for external plugins.

 New manifest.json features are:
 - startup and shutdown hooks
 - register mailboxes
 - pass config to mailbox parse_path
 - Added usage examples to demos plugin

 Necessary enhancements for external LEAP plugin.
Added sources_root to plugin loader.

- Added example to demos/manifest.json
- Removed subfolder hack for source files