Escape $cn when making distinguished_name command
Support passing arrays to API calls
Add `sslmate test` for testing cert installation
Add --invoice-note and --email-invoice-to options for customizing invoices
Strip private key (and other cruft) from certificate before importing
Add `sslmate mkconfig` for generating server config for a cert
Output interactive messages to stdout, not stderr
sslmate test: output bad results to stderr
sslmate test: output results to stdout only

If I output bad results to stderr, it makes it impossible to distinguish
bad test results from other errors, such as non-existent common name or
API authentication error.

To filter out OK results, it's easy enough to do:

sslmate test www.example.com | grep -v ': Good$'

This effectively reverts d45ddd75ac1dc2175cdd965489d873f8752ca74b.
Output informational messages to stdout instead of stderr

stderr is now reserved for error messages only, which makes it easier
to use sslmate in an automated fashion.
Add stubs for future --quiet option
Fix bug with argument parsing when -p was used
Add --temp option to `sslmate download`
Add --temp option to `sslmate buy`
Fix date of 0.5.0 release in NEWS file
Emphasize that temporary certs are self-signed
Update man page to document new features
Display a tip about `sslmate link` after typing password
sslmate test: support testing temporary certificates
Version 0.6.0