Unable to compile schema using avro-tools

Hi,

This may be a followup to https://github.com/common-workflow-language/common-workflow-language/issues/69 unless I'm mixing something up.

I'm using the current version of common-workflow-language (although the two tags don't seem to fare much better).

```
$ git status
On branch master
Your branch is up-to-date with 'origin/master'.

nothing to commit, working directory clean
$ git log | head
commit 791f4ef1dea83aed7827b679e179c634db7c0095
Author: Peter Amstutz
Date: Mon Nov 30 14:23:50 2015 -0500

No longer assume "#main" as entry point if there is more than one valid entry
point in a file.

```

When I use the schema_salad project to generate an avro schema, that succeeds.

```
$ python -mschema_salad --print-avro ~/common-workflow-language/draft-3/cwl-avro.yml > cwl.avsc
/home/dyuen/schema_salad/schema_salad/__main__.py 1.0.6
```

However, when I attempt to compile the schema, the following happens:

```
$ java -jar avro-tools-1.7.7.jar compile schema cwl.avsc cwl
Input files to compile:
cwl.avsc
Exception in thread "main" org.apache.avro.SchemaParseException: Illegal character in: draft-3.dev1
at org.apache.avro.Schema.validateName(Schema.java:1083)
at org.apache.avro.Schema.access$200(Schema.java:79)
at org.apache.avro.Schema$EnumSchema.(Schema.java:684)
at org.apache.avro.Schema.parse(Schema.java:1234)
at org.apache.avro.Schema.parse(Schema.java:1272)
at org.apache.avro.Schema$Parser.parse(Schema.java:965)
at org.apache.avro.Schema$Parser.parse(Schema.java:932)
at org.apache.avro.tool.SpecificCompilerTool.run(SpecificCompilerTool.java:73)
at org.apache.avro.tool.Main.run(Main.java:84)
at org.apache.avro.tool.Main.main(Main.java:73)

```