Annotated the DatabaseDao class as default

Added the annotation @Primary to the DatabaseDao in order to tag 
it as the default class for dependecy injection via 'autowiring'. 
Will be needed when sub-classes of this class are introduced.
Change visibility of fields to private.
Change certain variables to class members.

Also add getters for these. This makes it possible for these properties to
be altered in subclasses.
Whitespace
Merge pull request #20 from marcjansen/dbc-init

Refactor DatabaseContentInitializer
Give DB content initializer a getter for dbDao.
Merge pull request #21 from marcjansen/init-dao-getter

Give DB content initializer a getter for dbDao.