Add .projections.json configuration file

Editor plugins, like @tpope's vim-projectionist, can make use of this
configuration file to enable easy jumping between "alternate" files,
among other features. For example, with this configuration and
vim-projectionist installed, you can now be editing a lint and execute
`:A` to jump to that lint's spec file. This will save some time when
working with this project.

https://github.com/tpope/vim-projectionist

Change-Id: Ic7f96d5eb4398c0ee011929bce640a195ee204d3
Reviewed-on: http://gerrit.causes.com/45430
Tested-by: jenkins <[email protected]>
Reviewed-by: Shane da Silva <[email protected]>

Author: lencioni

.projections.json

@@ -0,0 +1,10 @@
+{
+  "lib/scss_lint/*.rb": {
+    "alternate": "spec/scss_lint/{}_spec.rb",
+    "type": "source"
+  },
+  "spec/scss_lint/*_spec.rb": {
+    "alternate": "lib/scss_lint/{}.rb",
+    "type": "test"
+  }
+}

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * Fix regression in rake task
 * Fix grammar of lints reported by `SelectorFormat`
+* Add .projections.json configuration file
 
 ## 0.31.0