Before:
```
C:\dev\tmp>py -2 -m flask run
Traceback (most recent call last):
File "C:\Python27\lib\runpy.py", line 174, in _run_module_as_main
"__main__", fname, loader, pkg_name)
File "C:\Python27\lib\runpy.py", line 72, in _run_code
exec code in run_globals
File "c:\dev\sourcetree\flask\flask\__main__.py", line 15, in <module>
main(as_module=True)
File "c:\dev\sourcetree\flask\flask\cli.py", line 523, in main
cli.main(args=args, prog_name=name)
File "c:\dev\sourcetree\flask\flask\cli.py", line 383, in main
return AppGroup.main(self, *args, **kwargs)
File "C:\Python27\lib\site-packages\click\core.py", line 697, in main
rv = self.invoke(ctx)
File "C:\Python27\lib\site-packages\click\core.py", line 1066, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "C:\Python27\lib\site-packages\click\core.py", line 895, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "C:\Python27\lib\site-packages\click\core.py", line 535, in invoke
return callback(*args, **kwargs)
File "C:\Python27\lib\site-packages\click\decorators.py", line 64, in new_func
return ctx.invoke(f, obj, *args[1:], **kwargs)
File "C:\Python27\lib\site-packages\click\core.py", line 535, in invoke
return callback(*args, **kwargs)
File "c:\dev\sourcetree\flask\flask\cli.py", line 433, in run_command
app = DispatchingApp(info.load_app, use_eager_loading=eager_loading)
File "c:\dev\sourcetree\flask\flask\cli.py", line 153, in __init__
self._load_unlocked()
File "c:\dev\sourcetree\flask\flask\cli.py", line 177, in _load_unlocked
self._app = rv = self.loader()
File "c:\dev\sourcetree\flask\flask\cli.py", line 238, in load_app
rv = locate_app(self.app_import_path)
File "c:\dev\sourcetree\flask\flask\cli.py", line 91, in locate_app
__import__(module)
File "C:\dev\tmp\error.py", line 1, in <module>
import whatisthisidonteven
ImportError: No module named whatisthisidonteven
```
After:
```
C:\dev\tmp>py -2 -m flask run
Usage: python -m flask run [OPTIONS]
Error: There was an error trying to import the app (error):
Traceback (most recent call last):
File "c:\dev\sourcetree\flask\flask\cli.py", line 91, in locate_app
__import__(module)
File "C:\dev\tmp\error.py", line 1, in <module>
import whatisthisidonteven
ImportError: No module named whatisthisidonteven```
* Don't rely on X-Requested-With for pretty print json response
* Fix test cases for pretty print json patch
* Fix gramma error in docs for pretty print json config
* Add changelog for JSONIFY_PRETTYPRINT_REGULAR
* Add tips for debug config with flask cli
`app.debug` and `app.config['DEBUG']` are not compatible with the `flask` script.
* Grammar fix
* Grammar fix
