fix(serve): delete dist on serve (#4293)
fix(serve): delete dist on serve (#4293)

`ng serve` will serve the app from memory, but it's easy to think that it just serves what's in `dist/`.

This way, `dist/` is deleted on `ng serve` and users will not have a `dist/` dir where they might think the files are being served from.

Partially address #4290
mikkeldamm/angular-cli,DevIntent/angular-cli,ReToCode/angular-cli,nwronski/angular-cli,angular/angular-cli,vsavkin/angular-cli,ocombe/angular-cli,cladera/angular-cli,mikkeldamm/angular-cli,RPGillespie6/angular-cli,eduesr/Angular,ocombe/angular-cli,geofffilippi/angular-cli,mham/angular-cli,dpmorrow/angular-cli,zoitravel/angular-cli,cladera/angular-cli,abdulmoizeng/angular-cli,LasTanzen/angular-cli,zoitravel/angular-cli,vsavkin/angular-cli,beeman/angular-cli,dzonatan/angular-cli,manekinekko/angular-cli,pedroapy/angular-cli,clydin/angular-cli,hansl/angular-cli,ampyc/angular-cli,maxime1992/angular-cli,geofffilippi/angular-cli,escorp/angular-cli,escorp/angular-cli,Brocco/angular-cli,DevIntent/angular-cli,Brocco/angular-cli,Brocco/angular-cli,clydin/angular-cli,intellix/angular-cli,ampyc/angular-cli,intellix/angular-cli,DevIntent/angular-cli,mikkeldamm/angular-cli,catull/angular-cli,delasteve/angular-cli,olivercs/angular-cli,eduesr/Angular,vsavkin/angular-cli,beeman/angular-cli,niklas-dahl/angular-cli,Brocco/angular-cli,olivercs/angular-cli,catull/angular-cli,dpmorrow/angular-cli,ampyc/angular-cli,geofffilippi/angular-cli,nwronski/angular-cli,LasTanzen/angular-cli,maxime1992/angular-cli,garoyeri/angular-cli,ReToCode/angular-cli,delasteve/angular-cli,abdulmoizeng/angular-cli,angular/angular-cli,geofffilippi/angular-cli,niklas-dahl/angular-cli,hansl/angular-cli,filipesilva/angular-cli,ocombe/angular-cli,intellix/angular-cli,filipesilva/angular-cli,escorp/angular-cli,FrozenPandaz/angular-cli,FrozenPandaz/angular-cli,DevIntent/angular-cli,pedroapy/angular-cli,catull/angular-cli,catull/angular-cli,hansl/angular-cli,zoitravel/angular-cli,DevIntent/angular-cli,olivercs/angular-cli,dpmorrow/angular-cli,pedroapy/angular-cli,ValeryVS/angular-cli,clydin/angular-cli,garoyeri/angular-cli,eduesr/Angular,gelliott181/angular-cli,angular/angular-cli,nickroberts/angular-cli,dzonatan/angular-cli,LasTanzen/angular-cli,gelliott181/angular-cli,RPGillespie6/angular-cli,cladera/angular-cli,beeman/angular-cli,manekinekko/angular-cli,nickroberts/angular-cli,filipesilva/angular-cli,delasteve/angular-cli,abdulmoizeng/angular-cli,ValeryVS/angular-cli,ocombe/angular-cli,RicardoVaranda/angular-cli,FrozenPandaz/angular-cli,ValeryVS/angular-cli,ReToCode/angular-cli,maxime1992/angular-cli,RicardoVaranda/angular-cli,beeman/angular-cli,niklas-dahl/angular-cli,hansl/angular-cli,RicardoVaranda/angular-cli,mham/angular-cli,gelliott181/angular-cli,ocombe/angular-cli,nickroberts/angular-cli,nwronski/angular-cli,clydin/angular-cli,mham/angular-cli,garoyeri/angular-cli,RPGillespie6/angular-cli,angular/angular-cli,dzonatan/angular-cli,manekinekko/angular-cli,filipesilva/angular-cli,Brocco/angular-cli