refactor web installer code to created C4::Installer

refactor web installer code to created C4::Installer

Created a new module, C4::Installer, which embodies
most of the code from installer/install.pl that handles
identifying and loading SQL scripts and setting the
Version, marcflavour, FrameworksLoad, and NoZebra
system preferences.

With C4::Installer, it is now easier to automate
initializing and populating a Koha database.  This will
help allow the test suite to set up a test database
in order to run DB-dependent tests, as well as write
a command-line installer which may be of use to hosts
that need to support multiple Koha databases.

Signed-off-by: Galen Charlton <galen.charlton@liblime.com>
Signed-off-by: Joshua Ferraro <jmf@liblime.com>