Update to latest scaffold

[pbrisbin]

Benefits:

• ClassyPrelude
• Better, ENV-based configuration
• Better development tools (handler/db)
• Better logging format
• Consist, stylish-haskell-formatted source
• Remove some unused files

Notes:

The process went like this:

• Clone the latest scaffold and checkout the postgres branch
• Update our cabal file to match the scaffold
• Remove all halcyon constraint files
• Remove the --enable-test compilation flag (this stops halcyon from building carnival itself as part of the sandbox step)
• bin/halcyon-build --dependencies-only
• cp missing files from yesod-scaffold
• rm extra files from current directory
• vimdiff each shared file; adjust as needed
• Try to compile Application.hs; fix errors
• Add --enable-test back, bin/halcyon-build, bring back constraints files
• Try yesod devel / yesod test; fix errors

I reformatted some code (Application.hs, TestImport.hs) to match the scaffold even though it was already functionally the same. This made this update and should make future updates easier.

I made it so that lists (exports, imports, dependencies, extensions, etc) match the scaffold exactly, then a blank line, then anything additional we need (alphabetized). There were only a few places where it didn't make sense to follow this exactly (e.g. TestImport's import Test.Hspec), but I did attempt to keep a vimdiff against the scaffold as readable as possible. This and the scaffold's use of stylish-haskell means that this code-base doesn't match our style guide completely -- I think that's OK.

[jferris]

Nice, it will be good to work with the latest Yesod stuff, especially classy-prelude. The settings changes are interesting, too.

[pbrisbin]

@jferris any more thoughts before I merge this and try it on staging?

(I'll also wait for Travis)

[jferris]

No, this looks good to me.

[mietek]

FYI — you should be able to use HALCYON_IGNORE_ALL_CONSTRAINTS instead of having to remove constraints files.