JBDS-3319 because packed size is less than expanded size on disk, add a 400M buffer to the size of the install >> master

[nickboldt]

No description provided.

[dgolovin]

-1.
We cannot calculate size easy way, but just adding 400m to wrong size is not going to work ether, because we have two peaces jbds and jbeap.

[dgolovin]

Look at https://github.com/dgolovin/jbdevstudio-product/blob/master/installer/src/panels/com/jboss/devstudio/core/installer/UpdatePacksPanel.java#L18

[nickboldt]

But the size predicted for the JBDS standalone and JBDS+EAP installs are different but consistently inaccurate, so an arbitrary bump would at least cover the install size and provide a bit more room, too.

Is it better to have a bad calculation that tells users they need LESS space than they actually do, or a bad calculation that tells users they need MORE space than is actuall required?

If we can't accurately calculate the number, I think erring on the side of "you need more space" is better than "you started the install and ran out of room".

[nickboldt]

Replaced by #261.