Fix build on low end VPS

[hunmar]

FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory

[alireza0]

I cant find a reason for building docker image in a low memory VPS when builded package is always available.
If you have 2G ram VM and want to use V8 garbage collector, then this amount is high!
It is better to let people configure it in case of their need, instead of hard-coding to 2G