pkg/wait: extend wait timeout in TestWaitTime
pkg/wait: extend wait timeout in TestWaitTime

Fix this error happening on travis:
```
--- FAIL: TestWaitTime-2 (0.01s)
		wait_time_test.go:46: cannot receive from ch as expected
```

a-robinson/etcd,endocode/etcd,dnaeon/etcd,ajityagaty/etcd,sebrandon1/etcd,fasaxc/etcd,chipironcin/etcd,sofuture/etcd,luxas/etcd,dannysauer/etcd,visheshnp/etcd,mkumatag/etcd,luxas/etcd,YuleiXiao/etcd,li-ang/etcd,li-ang/etcd,mkumatag/etcd,lumjjb/etcd,dnaeon/etcd,rnaveiras/etcd,ravigadde/etcd,linuxcer/etcd,mqliang/etcd,yudai/etcd,rnaveiras/etcd,coreos/etcd,etcd-io/etcd,mqliang/etcd,xiang90/etcd,lorneli/etcd,oscarrr110/etcd,glycerine/etcd,purpleidea/etcd,jlamillan/etcd,sayden/etcd,YuleiXiao/etcd,plasticbox/etcd,linuxcer/etcd,sinsharat/etcd,rchicoli/etcd,raoofm/etcd,tamird/etcd,lumjjb/etcd,jonboulle/etcd,fasaxc/etcd,westhood/etcd,swingbach/etcd,westhood/etcd,siddontang/etcd,bdarnell/etcd,mickep76/etcd,yudai/etcd,raoofm/etcd,vimalk78/etcd,sofuture/etcd,heyitsanthony/etcd,ktateish/etcd,whuwxl/etcd,bdarnell/etcd,a-robinson/etcd,glycerine/etcd,insequent/etcd,sinsharat/etcd,bluebreezecf/etcd,gyuho/etcd,vimalk78/etcd,zaphod-concur/etcd,akauppi/etcd,joshix/etcd,nekto0n/etcd,etcd-io/etcd,HideoYamauchi/etcd,mkumatag/etcd,bluebreezecf/etcd,wantonsolutions/dinv-etcd,armstrongli/etcd,cchamplin/etcd,achanda/etcd,ajityagaty/etcd,cockroachdb/etcd,Timer/etcd,glevand/coreos--etcd,etcd-io/etcd,HideoYamauchi/etcd,nekto0n/etcd,handsomesun/etcd,rnaveiras/etcd,whuwxl/etcd,StorReduce/etcd,xiang90/etcd,sebrandon1/etcd,gyuho/etcd,tamird/etcd,armstrongli/etcd,shawnps/etcd,tguangch/etcd,endocode/etcd,shawnps/etcd,heyitsanthony/etcd,joshix/etcd,ktateish/etcd,ravigadde/etcd,sayden/etcd,CrazyJvm/etcd,OyTao/etcd_learning,coreos/etcd,ajityagaty/etcd,plasticbox/etcd,hongchaodeng/etcd,qqsun8819/etcd,Timer/etcd,qqsun8819/etcd,jlamillan/etcd,wantonsolutions/dinv-etcd,dannysauer/etcd,rchicoli/etcd,CrazyJvm/etcd,lorneli/etcd,cockroachdb/etcd,swingbach/etcd,fanminshi/etcd,handsomesun/etcd,jonboulle/etcd,mickep76/etcd,siddontang/etcd,akauppi/etcd,cchamplin/etcd,tguangch/etcd,zaphod-concur/etcd,chipironcin/etcd,glevand/coreos--etcd,achanda/etcd,mqliang/etcd,StorReduce/etcd,OyTao/etcd_learning,fasaxc/etcd,hongchaodeng/etcd,visheshnp/etcd,insequent/etcd,wantonsolutions/dinv-etcd,purpleidea/etcd,fanminshi/etcd,oscarrr110/etcd