[Java] Print char fields as char instead of numeric (when primitiveType="char")

[pcdv]

Tentative fix for #1087

[mikeb01]

Is it possible to include a test for this?

[pcdv]

I wanted to add a test in JavaGeneratorTest but most tests are already failing with:

java.lang.IllegalStateException: Invalid property name='false' please correct the schema or consider setting system property: sbe.keyword.append.token

at uk.co.real_logic.sbe.generation.java.JavaUtil.formatForJavaKeyword(JavaUtil.java:178)
at uk.co.real_logic.sbe.generation.java.JavaGenerator.generateEnumValues(JavaGenerator.java:2243)
at uk.co.real_logic.sbe.generation.java.JavaGenerator.generateEnum(JavaGenerator.java:1980)
at uk.co.real_logic.sbe.generation.java.JavaGenerator.generateTypeStubs(JavaGenerator.java:209)
at uk.co.real_logic.sbe.generation.java.JavaGenerator.generate(JavaGenerator.java:257)
at uk.co.real_logic.sbe.generation.java.JavaGeneratorTest.shouldGenerateRepeatingGroupCountLimits(JavaGeneratorTest.java:494)