Make range param of delete op inclusive

Fixes #54
Merge pull request #55 from andylolz/54-inclusive-delete

Make range param of delete op inclusive
[docs][xs]: tweak to markdown link for main example on front page (was not rendering for me correctly).
[README][s]: instructions re deployment on heroku.
Merge branch 'master' of github.com:okfn/datapipes
Fix typo
Use transforms instead of HOFs.

This seems like the more nodey way to do it, and has advantages when it
comes to dropping in third party libraries e.g. unzip and csv.

This also moves the doc endpoints.

Some operations have been temporarily renamed.
Hack to map from url ops to required form
Use node-csv for rendering, too
Send the right content-type header
Bit of tidying up
Range param of delete op should still be inclusive
Update travis requirements
Clarify exactly what outcsv is doing.

Outcsv is operating synchronously, but on just one line at a time -
turning arrays into strings and pushing them out. If we do want it to
operate asynchronously, I think we need to make it a duplex.
Set a default content type of text/plain
Merge pull request #57 from andylolz/56-node-transforms

Use node transforms instead of HOFs
Prevent favicon 500s on text/plain output
Add a tail operation (with some tests)

Fixes #22.
Tidy up tests a little
Make delete use dynamic row indexes.

Fixes #59.