Add missing information about the first example in README.md
Clean up example: use context manager when opening files (already done elsewhere in the file), use  rather than %s, remove trailing spaces on a number of lines, break lines at under 80 characters
Merge pull request #269 from jeffknupp/master

Add missing information about the first example in README.md; clean up example code
Don't try to mail errors when missing config.
Merge pull request #271 from jcrobak/dont-email-none

Don't try to mail errors when missing config.
Merge branch 'master' of https://github.com/spotify/luigi
Move redshift to contrib
Convert indentation to 4 spaces
Extract a common superclass to postgres and redshift
Add a call to init_copy before running the copy
Rename redshit's copy_attributes to copy_options
Make copy_options an abstract property