Add CONTRIBUTING.md to take advantage of new GitHub feature.
Add CONTRIBUTING.md to take advantage of new GitHub feature.

GitHub recently added a feature that will display a link to the project's contribution
policies when an issue or pull request is created; this file provides a link to our wiki
page with those policies.

dbremner/bde,frutiger/bde,idispatch/bde,saxena84/bde,bowlofstew/bde,che2/bde,dbremner/bde,apaprocki/bde,saxena84/bde,abeels/bde,dharesign/bde,bloomberg/bde,che2/bde,abeels/bde,minhlongdo/bde,abeels/bde,che2/bde,dharesign/bde,mversche/bde,RMGiroux/bde-allocator-benchmarks,bloomberg/bde,osubboo/bde,idispatch/bde,jmptrader/bde,apaprocki/bde,idispatch/bde,bloomberg/bde-allocator-benchmarks,bloomberg/bde,osubboo/bde,osubboo/bde,RMGiroux/bde-allocator-benchmarks,dbremner/bde,abeels/bde,bloomberg/bde-allocator-benchmarks,apaprocki/bde,dharesign/bde,minhlongdo/bde,RMGiroux/bde-allocator-benchmarks,che2/bde,minhlongdo/bde,saxena84/bde,bowlofstew/bde,gbleaney/Allocator-Benchmarks,abeels/bde,dbremner/bde,bowlofstew/bde,bloomberg/bde-allocator-benchmarks,bowlofstew/bde,dharesign/bde,gbleaney/Allocator-Benchmarks,bloomberg/bde,osubboo/bde,RMGiroux/bde-allocator-benchmarks,mversche/bde,mversche/bde,apaprocki/bde,bloomberg/bde-allocator-benchmarks,abeels/bde,frutiger/bde,saxena84/bde,jmptrader/bde,frutiger/bde,idispatch/bde,bloomberg/bde-allocator-benchmarks,gbleaney/Allocator-Benchmarks,minhlongdo/bde,RMGiroux/bde-allocator-benchmarks,mversche/bde,jmptrader/bde,gbleaney/Allocator-Benchmarks,bloomberg/bde,frutiger/bde,jmptrader/bde,apaprocki/bde