changes for upgrade to dw 3.0, jersey > 2.25

[jaredstehler]

Support migrating to jersey 2.26+, which has breaking changes in the hk2 ServiceLocator.

• Remove/replace abandoned dep: com.squarespace.jersey2-guice:jersey2-guice-impl -- implementing HK2 to Guice Bridge in GuiceComponentProvider
  • This impl is inspired by the spring4 injection provider
  • I'm getting around the chicken-egg issue of referencing the InjectionManager in the guice module via static injection on server context init.
• Upgrade dropwizard deps to 2.1.x -- 2.0+ has jersey 2.26+, and 2.1 includes a fix to support slf4j 2.x, logback 1.3+