fix parts being undefined when referenced by sections in vimrc (#207).

t/section.vim

@@ -1,6 +1,3 @@
-call airline#init#bootstrap()
-call airline#extensions#load()
-
 function! SectionSpec()
 endfunction
 
@@ -11,6 +8,11 @@ describe 'section'
     call airline#parts#define_function('func', 'SectionSpec')
   end
 
+  it 'should be able to reference default parts'
+    let s = airline#section#create(['paste'])
+    Expect s == '%{airline#util#wrap(airline#parts#paste(),0)}'
+  end
+
   it 'should create sections with no separators'
     let s = airline#section#create(['text', 'raw', 'func'])
     Expect s == '%{airline#util#wrap("text",0)}raw%{airline#util#wrap(SectionSpec(),0)}'
@@ -43,6 +45,7 @@ describe 'section'
   end
 
   it 'should parse out a section from the distro'
+    call airline#extensions#load()
     let s = airline#section#create(['whitespace'])
     Expect s =~ 'airline#extensions#whitespace#check'
   end