Minor updates

[k0001]

@Gabriel439 I share some minor updates here:

• I bumped the upper-bound dependency on exceptions (see https://github.com/fpco/stackage/issues/443). No other dependencies need updating (http://packdeps.haskellers.com/feed?needle=pipes-safe)
• I removed an unused import GHC was complaining about when compiling the package.
• I noticed the package was missing a changelog.md file, which when named like that, is readily picked up by Hackage and linked from the package's description page. I took the liberty of adding it for you so that it is easier for users of your library to know what are the changes between versions.
• I increased the version number to 2.1.1 so that you can readily ship this.

Please let me know if you think I should change something here.

Thanks.

[Gabriella439]

Looks good!

For some reason the version on Hackage is actually ahead of the version on Github. However, I've used hdiff and it looks like the only difference between Hackage and Github is the version number. I sometimes have a habit of changing the version number right before uploading to Hackage and forgetting to commit the number to Github.

Could you just quickly modify your pull request to use version 2.2.1?

[k0001]

Done. Bumped version to 2.2.1

[Gabriella439]

Alright, I just uploaded this to Hackage. Thanks for taking the time to fix this! :)