[#82979704] Update ChangeLog to start feature "Update envetcd with output file option"

https://www.pivotaltracker.com/story/show/82979704
[#82979704] Added pull request url to ChangeLog

https://github.com/zvelo/envetcd/pull/2
add output option to write stdout of command to a file

Signed-off-by: Joshua Rubin <jrubin@zvelo.com>
bump version to 0.0.4

Signed-off-by: Joshua Rubin <jrubin@zvelo.com>