CURATOR-67 defer creation of serializer

Instead of immediately creating a new JSONInstanceSerializer we can
defer until build() is actually called. This lets users specify their
own serializers and avoids issues where there may be version conflicts.
CURATOR-67 defer creation of serializer

Instead of immediately creating a new JSONInstanceSerializer we can
defer until build() is actually called. This lets users specify their
own serializers and avoids issues where there may be version conflicts.

This closes #30
Merge branch 'CURATOR-67' of https://github.com/madrob/curator into CURATOR-67
CURATOR-67 - Removed the TestServiceDiscoveryBuilder test from the
discovery package as it does not build there (permission issues), and is
already present in the discovery/details package. Removed unnecessary
imports from the discovery/details version.