Improve server crash notification at startup

Notify the user if the server crashed during server polling at startup.

autoload/youcompleteme.vim

@@ -487,6 +487,7 @@ endfunction
 
 function! s:PollServerReady( timer_id )
   if !s:Pyeval( 'ycm_state.IsServerAlive()' )
+    exec s:python_command "ycm_state.NotifyUserIfServerCrashed()"
     " Server crashed. Don't poll it again.
     return
   endif

python/ycm/tests/youcompleteme_test.py

@@ -108,7 +108,7 @@ def RunNotifyUserIfServerCrashed( ycm, test, post_vim_message ):
   ycm._server_popen = MagicMock( autospec = True )
   ycm._server_popen.poll.return_value = test[ 'return_code' ]
 
-  ycm._NotifyUserIfServerCrashed()
+  ycm.OnFileReadyToParse()
 
   assert_that( ycm._logger.error.call_args[ 0 ][ 0 ],
                test[ 'expected_message' ] )

python/ycm/youcompleteme.py

@@ -186,8 +186,6 @@ class YouCompleteMe( object ):
     self._server_popen = utils.SafePopen( args, stdin_windows = PIPE,
                                           stdout = PIPE, stderr = PIPE )
 
-    self._NotifyUserIfServerCrashed()
-
 
   def _SetupLogging( self ):
     def FreeFileFromOtherProcesses( file_object ):
@@ -244,7 +242,7 @@ class YouCompleteMe( object ):
     return self._server_is_ready_with_cache
 
 
-  def _NotifyUserIfServerCrashed( self ):
+  def NotifyUserIfServerCrashed( self ):
     if ( not self._server_popen or self._user_notified_about_crash or
          self.IsServerAlive() ):
       return
@@ -371,7 +369,7 @@ class YouCompleteMe( object ):
 
   def OnFileReadyToParse( self ):
     if not self.IsServerAlive():
-      self._NotifyUserIfServerCrashed()
+      self.NotifyUserIfServerCrashed()
       return
 
     if not self.IsServerReady():