Include Cc and Bcc when sending MIME messages

It wasn't obvious enough that when sending MIME messages, all recipients need to be included in the 'to' parameter, otherwise those recipients will not receive the email.
fixed spelling error
Credentials
Typo fix
Note HTML is not sanitized from text/plain content
Credentials
Merge branch 'travis/creds' of https://github.com/mailgun/documentation into travis/creds

Conflicts:
	source/samples/change-pwd-credentials.rst
Merge pull request #38 from mailgun/travis/creds

Add SMTP Credentials Section
Merge pull request #36 from ramnes/master

Typo fix
Update user_manual.rst

Added a predefined template variable %recipient_email%
Merge pull request #35 from objectrocket/master

fixed spelling error
Merge pull request #39 from jesinwp/patch-1

Update user_manual.rst
Merge pull request #33 from RubenKruiswijk/patch-1

Include Cc and Bcc when sending MIME messages
Removal of Mailbox API references.
Merge pull request #40 from mailgun/MailboxEOL

Removal of Mailbox API references.
Merge pull request #1 from mailgun/master

Update fork from original
Added whitespace before backslash in cURL command

Ignoring a space before backslash "\" makes cURL read the parameters like this

    -d event='sent'-d event='opened' -d skip=1 -d limit=2

which throws the error __curl: (6) Couldn't resolve host 'event=opened'__
Added whitespace before backslash in cURL command
Added whitespace before backslash in cURL command
Added a backslash to the cURL command