Added Support for Metric Units

So I've added support for metric units. I created a SettingsFragment and added that to the navigation drawer, in the UI beneath Inventory.

Change highlights:
* Added SettingsFragment. Updated UI.
* Adjusted math for all vitals (og,fg,srm,ibu,etc.). The math seems to work correctly.
* Adjusted UI for RecipeStatsFragment. Displays kg/l instead of lb/gal when appropriate.

A couple notes:
* In my fork you may see a commit from teamviperstrike. That's me. I was logged into my github desktop client as my old development name. I committed another update for comment changes to verify I had the right account moving forward.
* Concerns:
 * 1: When I edit recipe volumes in the RecipeStatsFragment, they are not displayed in the RecipeFragment when going back. No matter the value, it always reverts to defaults and I cannot tell why.
 * 2: I am using SharedPreferences now for boil/batch volumes. I am concerned that these will be used in all recipes, as I cannot readily see how/where new recipes are given default values. I have not been able to test this due to my first concern.

I just need some help getting the RecipeFragment to display changes made in RecipeStatsFragment. All other areas (UI mainly) I can change once that is working.