Remove all mentions of Marmelade

[gracjan]

Marmelade is as good as dead now, see here: nicferrier/elmarmalade#92.

Remove all mentions of Marmelade from:

• README.md
• Makefile (package generation part)
• haskell-mode/wiki

Find out also about haskell-mode on marmelade mentions in external wikis or tutorials, contact respective authors, tell them to update.

[jhenahan]

Non-historical references to Marmalade have been purged from the wiki.

[gracjan]

@jhenahan: Great! Thanks!

Can you also prepare a pull request that removes Marmelade from README and Makefile?

[jhenahan]

Done, with #627.