make generation of symlink configurable

[sriv]

Expected behavior

the symlink to html-report binary is generated under reports/html-report. Allow users to disable this.

Actual behavior

the symlink is always generated, and as a result when copying over the reports folder, the symlink gets copied over as well. However it is not valid anymore, when accessed by a different user or in a different machine.

Steps to reproduce

1. gauge init js
2. gauge run specs
3. ls reports/html-report

Gauge version

Gauge version: 1.0.3
Commit Hash: b7ea2ee

Plugins
-------
csharp (0.10.6.nightly-2018-09-05)
dotnet (0.1.1.nightly-2018-09-11)
html-report (4.0.6)
java (0.6.8)
js (2.3.1)
python (0.3.4.nightly-2018-09-05)
ruby (0.5.2.nightly-2018-09-11)
screenshot (0.0.1)
spectacle (0.1.4.nightly-2018-07-30)
xml-report (0.2.1.nightly-2018-05-14)

[sriv]

On second thoughts, gauge saves the last run result only when save_execution_result is true.

html-report can use the same config and generate symlink only if save_execution_result=true

[negiDharmendra]

Make sense as the purpose of the symlink is to regenerate reports from the last run result.

[gaugebot]

The fix should be available in nightly >= 10-10-2018