internals: setting update.LATEST to "v1.1.0-dev1" fails with embedded CommandLineTools

This is mostly for @tetron

``` diff
diff --git a/cwltool/update.py b/cwltool/update.py
index 9e79b98a..495d2c19 100644
--- a/cwltool/update.py
+++ b/cwltool/update.py
@@ -133,7 +44,7 @@ DEVUPDATES = {
ALLUPDATES = UPDATES.copy()
ALLUPDATES.update(DEVUPDATES)

-LATEST = u"v1.0"
+LATEST = u"v1.1.0-dev1"
```
```
$ cwltool --debug tests/wf/scatter-wf4.cwl tests/wf/scatter-job2.json
Resolved 'tests/wf/scatter-wf4.cwl' to 'file:///home/mcrusoe/cwltool/tests/wf/scatter-wf4.cwl'
Validation exception
Tool definition file:///home/mcrusoe/cwltool/tests/wf/scatter-wf4.cwl#echo failed validation:
tests/wf/scatter-wf4.cwl:4:3: checking object `tests/wf/scatter-wf4.cwl#echo`
tests/wf/scatter-wf4.cwl:6:3: checking field `requirements`
tests/wf/scatter-wf4.cwl:1:1: checking item
tests/wf/scatter-wf4.cwl:6:3: Field `class` contains undefined reference to `file:///home/mcrusoe/cwltool/tests/wf/NetworkAccess`
Traceback (most recent call last):
File "/home/mcrusoe/cwltool/cwltool/workflow.py", line 619, in __init__
toolpath_object["run"], loadingContext)
File "/home/mcrusoe/cwltool/cwltool/load_tool.py", line 372, in load_tool
metadata=loadingContext.metadata)
File "/home/mcrusoe/cwltool/cwltool/load_tool.py", line 284, in validate_document
workflowobj, fileuri, checklinks=do_validate)
File "/home/mcrusoe/cwltool/env3/lib/python3.6/site-packages/schema_salad/ref_resolver.py", line 919, in resolve_all
self.validate_links(document, u"", all_doc_ids)
File "/home/mcrusoe/cwltool/env3/lib/python3.6/site-packages/schema_salad/ref_resolver.py", line 1091, in validate_links
raise errors[0]
```