Fixed error when building from schema with complex model properties

[mamonth]

Changes needed to support properties like 'some:property' widely used in API design. See HAL format for example.

[karlvr]

@mamonth thank you very much for this PR! I would love to only emit these quotes if they're needed... I wonder about adding a new Handlebars helper that could do that... is it a kind of quoteIdentifier? Interesting to think... TypeScript lets you do that but Java doesn't. We can add language-specific helpers, e.g. in typescript-common in the exportTemplates method.

Maybe it's quoteIdentifierIfNeeded and it looks for any characters in the serialised name that aren't legal and then quotes it. I guess it then also escapes quotes themselves using the escapeString function already in typescript-common.

Are you happy to try out these changes?

[karlvr]

@mamonth also could you please add a sample .yml test case that demonstrates the issue? That will then test it with all of the generators.

[mamonth]

Language specific helper seems like valid option. I wasn't able to dive in to architecture of generators deep enough to see this possibility.
And good point about test case.
I'll try to make it right :)