Creates a layouts/ folder for keymaps shared between keyboards (#1609)

* include variables and .h files as pp directives

* start layout compilation

* split ergodoxes up

* don't compile all layouts for everything

* might seg fault

* reset layouts variable

* actually reset layouts

* include rules.mk instead

* remove includes from rules.mk

* update variable setting

* load visualizer from path

* adds some more examples

* adds more layouts

* more boards added

* more boards added

* adds documentation for layouts

* use lowercase names for LAYOUT_

* add layout.json files for each layout

* add community folder, default keymaps for layouts

* touch-up default layouts

* touch-up layouts, some keyboard rules.mk

* update documentation for layouts

* fix up serial/i2c switches

layouts/community/ergodox/plums/readme.md

@@ -0,0 +1,11 @@
+# ErgoDox EZ Plums Configuration
+
+## Changelog
+
+* Apr 23, 2016 (v0.1.0): 
+  * Shortcut for iTerm2 quake style dropdown (Ctrl+`)
+  * Shortcut for screen/tmux (Ctrl+a)
+  * Shortcut for shush (Hyper+m)
+  * Combo modifier for LGUI + LALT
+
+![Plums](https://i.imgur.com/0HkgLvb.png)