Additional fixes around versioning.

[MayaKirova]

Additional fixes around getting/setting version dropdown content.

[zdrawku]

@dkamburov I guess you will test the change from Maya? We have documented a brief explanation on how to test typedoc-theme changes, I guess you will find it helpful:

1. npm run build of ig-typedoc-theme changes to build the package in the dist folder
2. "npm pack" to create a package (ig-typedoc-theme-1.0.0.tgz)
3. "cp ig-typedoc-theme-1.0.0.tgz ~"
4. Go to igniteui-angular project and execute "npm install ~/ig-typedoc-theme-1.0.0.tgz"
5. Build typedoc with any of the existing commands, lets use for example - npm run build:typedoc:en:production
6. Go to ..\igniteui-angular\dist\igniteui-angular\docs\typescript and run the html

Note: OR, you can use npm link but this sometimes gives problems