Update leaflet.toolbar-src.js

[WagnerSte]

Fixed compatibility issue with leaflet.draw as described in:

http://stackoverflow.com/questions/33348059/adding-l-control-draw-to-leaflet-manually

[coveralls]

Coverage remained the same at 93.701% when pulling 1bf51a9 on WagnerLoc:master into df9ecc6 on Leaflet:master.

[justinmanley]

Thanks for the pull request!

There's a little bit more that I need from you:

1. Please provide a means of reproducing the issue described in the Stack Overflow post. In particular, Leaflet.draw no longer seems to have an _initModeHandler method, so I wonder if this issue is still present, since I don't see it with the examples in this repo.
2. Please add the changes to the source files that resulted in the change to leaflet.toolbar-src.js. leaflet.toolbar-src.js is built by running grunt build:js in the root of this repository, and should always reflect the code under the src/ directory.