Use dib-python to run package-installs using the provided python
version. Automatically detect the python version for our
package-installs-squash since that runs outside the chroot.
Change-Id: I926022bcf8cbcd81b051026ffd5d6477650045ad
Packages are often also installed in both the pre-install.d and
post-install.d phases. This patch expands the package-installs element
to support declarative package support for these phases in addition to
the existing support for install.d. The actual install/uninstall logic
is moved to common scripts under bin/ so that it can be reused across
the different phases.
Change-Id: Id51d0bbad232737fc8b5ffaf016dec50cd5b66c9
