dockerlint incorrectly alerts on any commands included within a RUN<<HEREDOC stanza

[m-dunbar]

Issue details

dockerlint incorrectly reports errors for every line inside a RUN<<HEREDOC ... HEREDOC stanza.

Steps to reproduce/test case

1. create any Dockerfile
2. add any RUN<<EOF ... EOF stanza

Affected version(s)

All. Currently, I'm using the most recent version as of the date of this report (0.3.2).