Make toJson more JSONish

[tonicebrian]

In all HTTP services I make, I add an endpoint /build outputting the toJson result of the BuildInfo. That output is not fully JSON and thus I lack the ability of manipulating output. This pull request is for making that output a bit more JSONish without going full way about adding an external dependency like akka-http-spray-json.

Now I'm able to compare libraries compiled in two instances by doing things like:

curl localhost:8900/build | jq ".libraryDependencies | sort"

[dwijnand]

lgtm. it doesn't handle nested seqs/options, but that's probably not that common.

requesting an extra review by @eed3si9n

[eed3si9n]

How does the before and after look like? Is this going to be a breaking change for existing users of this feature?

[dwijnand]

there is a test (that changed). it tests that the code generator generates the right code. but there's no test for the JSON string value that results from running the generated code.

how meta^{can youget} 😄

[tonicebrian]

@eed3si9n Regarding breaking code for existing users, this PR is going to break code that parses libraryDependencies as a string

...
"libraryDependencies" : "scala.collection.Seq(org.scala-lang:scala-library:2.12.4, com.lihaoyi:acyclic:0.1.7:plugin->default(compile), .....)"
...

because now it will be:

...
"libraryDependencies" : ["org.scala-lang:scala-library:2.12.4", "com.lihaoyi:acyclic:0.1.7:plugin->default(compile)", .....]
...

I guess that if they were parsing the Json before, it is way easier to adapt the code so they have proper Json lists and options (to the first level of nesting as pointed by @dwijnand )

[eed3si9n]

ok. I'll be happy to merge this, but we should bump the version number to 0.9.0.