treat transcient bundles as configured

- "transcient bundle" - a bundle installed with :BundleInstall or interactively
  without being declared in .vimrc

- treat them the as if they were configured
- so everything works the same

- ie before this change helptags weren't generated automatically
  with `BundleInstall bundle` or with interactive mode

- it changes the way `:BundleClean` works, since it removes directories
  that aren't bundles
- FIX: `:source .vimrc` to let `:BundleClean` remove transcient bundles

- closes #99

autoload/vundle/config.vim

@@ -3,6 +3,7 @@ func! vundle#config#bundle(arg, ...)
   call s:rtp_rm_a()
   call add(g:bundles, bundle)
   call s:rtp_add_a()
+  return bundle
 endf
 
 func! vundle#config#init()

autoload/vundle/installer.vim

@@ -1,7 +1,7 @@
 func! vundle#installer#new(bang, ...) abort
   let bundles = (a:1 == '') ?
         \ g:bundles :
-        \ map(copy(a:000), 'vundle#config#init_bundle(v:val, {})')
+        \ map(copy(a:000), 'vundle#config#bundle(v:val, {})')
 
   let names = vundle#scripts#bundle_names(map(copy(bundles), 'v:val.name_spec'))
   call vundle#scripts#view('Installer',['" Installing bundles to '.expand(g:bundle_dir, 1)], names +  ['Helptags'])
@@ -83,7 +83,8 @@ endf
 
 func! vundle#installer#install_and_require(bang, name) abort
   let result = vundle#installer#install(a:bang, a:name)
-  let b = vundle#config#init_bundle(a:name, {})
+  let b = vundle#config#bundle(a:name, {})
+  call vundle#installer#helptags([b])
   call vundle#config#require([b])
   return result
 endf