Fix nodejs-server path issue in windows platform

[wing328]

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Description of the PR

To fix #6443

cc @CodeNinjai (2017/07) @frol (2017/07) @cliffano (2017/07)

[frol]

1. Is there a file path API for Java to avoid such an error-prone path concatenation implementation?
2. Why should all the dots (.) be replaced with a path separator? What if I have a folder with a dot in its name?

[wing328]

1. Not that I'm aware of and I agree the current solution is error-prone so I'm open to new ideas for a better implementation.

2. I do not know the reason. The logic was added before I joined this project. My suggestion is to keep the current behavior and try to come up with workaround/solution if users file an issue about it.

[frol]

1. OK

2. If you want to keep the current behavior, you should probably drop those parentheses to limit the replacement only for the apiPackage() string instead of the whole result:

   outputFolder + File.separator + output + File.separator + apiPackage().replace('.', File.separatorChar)
   

[wing328]

2. Done via e10c09d

[frol]

LGTM

[dlarr]

Doesn't work on Windows

Change 1
NodeJSServerCodegen.java line 88: back to

supportingFiles.add(new SupportingFile("writer.mustache", ("utils").replace(".", "/"), "writer.js"));

change 2 : NodeJSServerCodegen.java, line 172
Use this :

String replacement = (java.io.File.separator.equals("\\") ?  java.io.File.separator + java.io.File.separator : java.io.File.separator) 
        			+ implFolder + 
        			(java.io.File.separator.equals("\\") ?  java.io.File.separator + java.io.File.separator : java.io.File.separator) ;

[wing328]

@dlarr thanks for the review. I think my approach should still work.

Given that it does not impact Mac/Linux, I'll merge it and ask my friends to try it in their Windows box.