Using camal case for node file naming so the package can install on linux

[yugangw-msft]

Please comment if you have any concerns.
There is no well agreed on file naming conventions for node.js. (Python has one at https://www.python.org/dev/peps/pep-0008/)
We crossed checked several resources and we set on just using camel case for 2 reasons

1. Good Readability
2. Existing "node-sdk-for-node" uses this style, but just have not be consistent. Moving forward we will take efforts to get it be.

I list the resource we have read for references:
a. felixge/node-style-guide#30
b. https://github.com/joyent/node/tree/master/lib (see how the node.js team itself does)

Amar and I discussed whether we should use Pascal casing for file which export a single Class per point of "a" above. We are leaning to keep what we have for the reason of "2" above as it doesn't make too much difference.

Regardless, the main goal moving forward is to maintain the consistence