Add new build hook: before_postinstall
Add build hook before_postinstall to documentation
Merge pull request #917 from I2SE/before_postinstall

Add new build hook before_postinstall
Fix whitespace handling for vm_flags
Fix whitespace handling for box export
Update basics.md

Otherwise the build fails on ubuntu boxes
Merge pull request #918 from stenver/patch-1

Update basics.md
Merge pull request #919 from I2SE/fix_ws_handling

Fix vbox build if name contains spaces
Merge branch 'master' of github.com:narkisr/veewee