Created `.gitignore` file.
Created `.gitignore` file.

Closes #25
* Ignores the node_modules directory because it's not needed in the repository.
* Ignores the DS_STORE file on Mac because it's pointless committing that every time.
* Ignores npm log file because it's unnecessary to store that in the repository.
theiver9827/brain,richard512/brain,ThiagoGarciaAlves/brain,kustomzone/brain,Ossehoht/brain,dexterbrylle/brain,webmechanicx/brain,lichterschalter/brain,urandu/brain,mrStiven/brain,ClimbsRocks/warmBrain,BrainJS/brain.js,ClimbsRocks/brain,antares500/brain,andyfoster/brain,daysmingming/brain,gdseller/brain,renatoargh/brain,mcanthony/brain,elkingtonmcb/brain,saidimu/brain,datachand/brain,trongr/brain,martinstarman/brain,adrianseeley/brain,harthur/brain,nickpoorman/brain,kuychaco/brain,stndlkr200/brain,Django0505/brain,drewry/brain,dpraimeyuu/brain,chrisearl/brain,harthur-org/brain.js,valgaze/brain,ckknight/brain,harthur-org/brain,polymaths/brain