init whitespace extension to blank. fixes #226.

autoload/airline/init.vim

@@ -67,7 +67,7 @@ function! airline#init#bootstrap()
         \ })
   call airline#parts#define_raw('file', '%f%m')
   call airline#parts#define_raw('ffenc', '%{printf("%s%s",&fenc,strlen(&ff)>0?"[".&ff."]":"")}')
-  call airline#parts#define_empty(['hunks', 'branch', 'tagbar', 'syntastic'])
+  call airline#parts#define_empty(['hunks', 'branch', 'tagbar', 'syntastic', 'whitespace'])
 endfunction
 
 function! airline#init#sections()

t/extensions_default.vim

@@ -23,8 +23,8 @@ describe 'default'
 
   it 'should only render warning section in active splits'
     wincmd s
-    Expect airline#statusline(1) =~ 'whitespace'
-    Expect airline#statusline(2) !~ 'whitespace'
+    Expect airline#statusline(1) =~ 'warning'
+    Expect airline#statusline(2) !~ 'warning'
     wincmd c
   end
 end

t/init.vim

@@ -61,6 +61,7 @@ describe 'init'
     Expect airline#parts#get('branch').raw == ''
     Expect airline#parts#get('tagbar').raw == ''
     Expect airline#parts#get('syntastic').raw == ''
+    Expect airline#parts#get('whitespace').raw == ''
   end
 end