Allow Jackson features to be configured via the environment

Enhance JacksonAutoConfiguration to configure features on the
ObjectMapper it creates based on the following configuration
properties:

spring.jackson.deserialization.* = true|false
spring.jackson.generator.* = true|false
spring.jackson.mapper.* = true|false
spring.jackson.parser.* = true|false
spring.jackson.serialization.* = true|false

The final part of each property name maps onto an enum. The enums are:

deserialization: com.fasterxml.jackson.databind.DeserializationFeature
generator: com.fasterxml.jackson.core.JsonGenerator.Feature
mapper: com.fasterxml.jackson.databind.MapperFeature
parser: com.fasterxml.jackson.core.JsonParser.Feature
serialization: com.fasterxml.jackson.databind.SerializationFeature

Closes gh-1227