tools: require pandoc 1.16 for the site

For the {width=100 height=20} image attribute syntax.
Also give it a stack.yaml of its own for now, since hledger
is stuck at lts 4.2 for hledger-api.

site/hakyll-std/hakyll-std.hs

@@ -1,5 +1,5 @@
 #!/usr/bin/env stack
--- stack runghc --package hakyll --package pandoc
+-- stack runghc --package hakyll --package pandoc-1.16.0.2
 {-# LANGUAGE OverloadedStrings #-}
 {- |
 

site/hakyll-std/stack.yaml

@@ -0,0 +1,35 @@
+# For more information, see: http://docs.haskellstack.org/en/stable/yaml_configuration.html
+
+# Specifies the GHC version and set of packages available (e.g., lts-3.5, nightly-2015-09-21, ghc-7.10.2)
+resolver: lts-5.2
+
+# Local packages, usually specified by relative directory name
+packages:
+- '.'
+
+# Packages to be pulled from upstream that are not in the resolver (e.g., acme-missiles-0.3)
+extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+flags: {}
+
+# Extra package databases containing global packages
+extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: >= 1.0.0
+
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor