introduce a test that fails on "fixed" values
add support for "fixed" binary fields
support @AvroFixedSize annotation for declaration of "fixed" avro fields
improve naming and document the AvroFixedSize annotation
Merge branch 'master' into support-fixed-fields

Conflicts:
	src/main/java/com/fasterxml/jackson/dataformat/avro/AvroGenerator.java
Merge pull request #14 from joshng/support-fixed-fields

Support serializing "fixed" fields