* Did restructuring and made repo validation interceptor an optional bean instead as it makes it more clean
* Moved construction of FHIR servlet into a bean for better reuse of others that would like to depend directly on this library
* Disabled default validation enabled
What this commit has achieved:
1. Fixed failing tests in `ExampleServerR4IT` due to:
```
org.awaitility.core.ConditionTimeoutException: Condition with ca.uhn.fhir.jpa.starter.ExampleServerR4IT was not fulfilled within 10 seconds.
```
default await time from Awaitility is 10 seconds
2. Added entries in `.gitignore` related to STS IDE
- reverted mysql as default and used derby based on change request 6858c0d799 (r266028296) and updated readme to include specifics on configuring mysql
- defaulted to jetty configs on hapi.properties so that this starter app will outright work without changing any configs with mvn jetty:run
- updated subscription configs as it doesn't match already active subscription on subsequent runs using mysql as db
- updated project based path resolution and removed unused file .keep_hapi-fhir-jpaserver-starter
