Replace spaces with plus (+) signs (config/environment.chroot).

Spaces break chroot environment variables. Quick fix until we have
better way to export variables into chroot.

Signed-off-by: Ville Korhonen <ville.korhonen@ylioppilastutkinto.fi>
Merge environment into single-line variable.
Replace space with plus sign (+).
Fix path to building instructions.
Use HTTPS as protocol for digabi.fi.
Set browser upload dir default to our usb mount
Merge branch 'fix/chroot-variables'

* fix/chroot-variables:
  Replace space with plus sign (+).
  Merge environment into single-line variable.
  Replace spaces with plus (+) signs (config/environment.chroot).