Wrap testing import so testing libraries aren't required.
Wrap testing import so testing libraries aren't required.

Without this, the move of a bunch of utils into util.testing
combined with with the reference to util.testing in bokeh.__init__
meant that users would need a bunch of testing dependencies installed
just to run bokeh!

philippjfr/bokeh,ptitjano/bokeh,rs2/bokeh,schoolie/bokeh,jplourenco/bokeh,ChinaQuants/bokeh,muku42/bokeh,tacaswell/bokeh,clairetang6/bokeh,msarahan/bokeh,gpfreitas/bokeh,aavanian/bokeh,clairetang6/bokeh,gpfreitas/bokeh,azjps/bokeh,mindriot101/bokeh,maxalbert/bokeh,jakirkham/bokeh,dennisobrien/bokeh,mindriot101/bokeh,jakirkham/bokeh,aavanian/bokeh,mindriot101/bokeh,draperjames/bokeh,aiguofer/bokeh,schoolie/bokeh,dennisobrien/bokeh,quasiben/bokeh,timsnyder/bokeh,ChinaQuants/bokeh,KasperPRasmussen/bokeh,Karel-van-de-Plassche/bokeh,ptitjano/bokeh,aavanian/bokeh,philippjfr/bokeh,draperjames/bokeh,msarahan/bokeh,htygithub/bokeh,bokeh/bokeh,gpfreitas/bokeh,ericmjl/bokeh,DuCorey/bokeh,ptitjano/bokeh,Karel-van-de-Plassche/bokeh,muku42/bokeh,timsnyder/bokeh,timsnyder/bokeh,bokeh/bokeh,mindriot101/bokeh,stonebig/bokeh,rs2/bokeh,aiguofer/bokeh,Karel-van-de-Plassche/bokeh,DuCorey/bokeh,khkaminska/bokeh,phobson/bokeh,evidation-health/bokeh,jplourenco/bokeh,KasperPRasmussen/bokeh,aiguofer/bokeh,deeplook/bokeh,srinathv/bokeh,Karel-van-de-Plassche/bokeh,DuCorey/bokeh,azjps/bokeh,stonebig/bokeh,rs2/bokeh,khkaminska/bokeh,percyfal/bokeh,justacec/bokeh,percyfal/bokeh,DuCorey/bokeh,msarahan/bokeh,khkaminska/bokeh,maxalbert/bokeh,maxalbert/bokeh,justacec/bokeh,phobson/bokeh,evidation-health/bokeh,maxalbert/bokeh,srinathv/bokeh,bokeh/bokeh,stonebig/bokeh,ericmjl/bokeh,tacaswell/bokeh,aavanian/bokeh,dennisobrien/bokeh,jplourenco/bokeh,timsnyder/bokeh,evidation-health/bokeh,jakirkham/bokeh,aiguofer/bokeh,ChinaQuants/bokeh,schoolie/bokeh,bokeh/bokeh,ptitjano/bokeh,DuCorey/bokeh,percyfal/bokeh,schoolie/bokeh,Karel-van-de-Plassche/bokeh,msarahan/bokeh,srinathv/bokeh,timsnyder/bokeh,ptitjano/bokeh,khkaminska/bokeh,htygithub/bokeh,bokeh/bokeh,azjps/bokeh,muku42/bokeh,deeplook/bokeh,ericmjl/bokeh,ChinaQuants/bokeh,philippjfr/bokeh,KasperPRasmussen/bokeh,htygithub/bokeh,draperjames/bokeh,azjps/bokeh,phobson/bokeh,stonebig/bokeh,clairetang6/bokeh,aiguofer/bokeh,muku42/bokeh,KasperPRasmussen/bokeh,philippjfr/bokeh,draperjames/bokeh,aavanian/bokeh,azjps/bokeh,ericmjl/bokeh,justacec/bokeh,percyfal/bokeh,draperjames/bokeh,schoolie/bokeh,tacaswell/bokeh,phobson/bokeh,deeplook/bokeh,evidation-health/bokeh,jakirkham/bokeh,jplourenco/bokeh,phobson/bokeh,dennisobrien/bokeh,htygithub/bokeh,justacec/bokeh,KasperPRasmussen/bokeh,percyfal/bokeh,quasiben/bokeh,rs2/bokeh,jakirkham/bokeh,dennisobrien/bokeh,quasiben/bokeh,rs2/bokeh,gpfreitas/bokeh,philippjfr/bokeh,deeplook/bokeh,tacaswell/bokeh,clairetang6/bokeh,srinathv/bokeh,ericmjl/bokeh