Reduce bunch of lines in rails

[Prakriti-nith]

This PR aims to remove a bunch of lines that occur in the head tag in rails. Dependent JS and CSS files are shifted to vendor/assets/javascripts and vendor/assets/stylesheets respectively. These can be included in the app/assets/javascripts/application.js file as:

//= require highcharts/highcharts                                                           
//= require highcharts/highcharts-more
//= require highcharts/map
//= require googlecharts/google_visualr
//= require googlecharts/loader

and include the below line in head of the layout file:
<%= javascript_include_tag "application" %>

Note: The previous method to use <%=raw Daru::View.dependent_script(:highcharts) %> will also work.

[coveralls]

Pull Request Test Coverage Report for Build 665

• 5 of 7 (71.43%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.0006%) to 98.015%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/daru/view/adapters/nyaplot/iruby_notebook.rb	0	2	0.0%

Totals
Change from base Build 664:	0.0006%
Covered Lines:	3111
Relevant Lines:	3174

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💛 - Coveralls

[Shekharrajak]

Please add examples for these changes and refer it here.