Move vim settings out of plugins to ensure they all get correctly loaded after everything else [Fix #373]

vim/settings/airline.vim

@@ -0,0 +1,7 @@
+let g:airline_left_sep = '⮀'
+let g:airline_left_alt_sep = '⮁'
+let g:airline_right_sep = '⮂'
+let g:airline_right_alt_sep = '⮃'
+let g:airline_branch_prefix = '⭠ '
+let g:airline_readonly_symbol = '⭤'
+let g:airline_linecolumn_prefix = '⭡'