Connecting themes 'Cosmo'

Signed-off-by: Valentin Popov <info@valentineus.link>

.gitmodules

@@ -2,3 +2,7 @@
 	path = _scss/bootstrap
 	url = https://github.com/twbs/bootstrap-sass.git
 	branch = 3.3-stable
+[submodule "bootswatch"]
+	path = _scss/bootswatch
+	url = https://github.com/thomaspark/bootswatch.git
+	branch = master

_scss/base/_bootstrap.scss

@@ -1 +1,3 @@
+@import 'bootswatch/cosmo/_variables.scss';
 @import 'bootstrap/assets/stylesheets/bootstrap';
+@import 'bootswatch/cosmo/_bootswatch.scss';