Rename send_with_smtp? to smtp_configured?
Sanitize SMTP user in from address

This fixes a common case where the SMTP user has the form of an email
address. The "from" email address that feed2email generated had the @
character twice, causing the SMTP server to complain.
Mention Mailgun in SMTP section of README file
Add config option for sender email address (from)
Log backtrace on error
Shorten from method with string interpolation
Add config option for log verbosity
List msmtp and Postfix as examples in README file
Add text/plain part in email messages
Strip HTML from email subject and body title
Clean up methods in Feed2Email::Mail
Update change log
Bump to version 0.5.0