[GoogleCharts] Updating of jsapi causes error in GoogleCharts

[Prakriti-nith]

Updating the jsapi is causing error in the formation of GoogleCharts. (Refer this comment). For now, I have commented out that portion in this commit.
For the usage of these js files refer updating, limitations and release notes of Google Chart loading.

[Shekharrajak]

I think we should remove the google chart js files. Anyways at the end, it need internet so having these files in the gem assets folder or directly using the link while using GoogleChart adpater is same (By removing these files will reduce the gem size #127).

I believe Nyaplot way of including script tag should be used in init_script for GoogleChart adapter.