Create 2018-04-26-dc-seven-weeks.md
Create 2018-04-26-dc-seven-weeks.md

Don't merge yet
datacarpentry/datacarpentry.github.io,ErinBecker/datacarpentry.github.io,ErinBecker/datacarpentry.github.io,datacarpentry/datacarpentry.github.io,datacarpentry/datacarpentry.github.io,ErinBecker/datacarpentry.github.io,ErinBecker/datacarpentry.github.io