[#68217860] PDF Generator accepts an array of sources

Signed-off-by: Elana Koren <ekoren@pivotallabs.com>
[#68217860] Generating a sitemap returns an array of working links

Signed-off-by: Elana Koren <ekoren@pivotallabs.com>
[#68217860] Docset PDF is generated by default.

Signed-off-by: Elana Koren <ekoren@pivotallabs.com>
[#68217860] Full-book PDF generates only when sitemap is not empty

Signed-off-by: Nikhil Gajwani <ngajwani@pivotallabs.com>
Signed-off-by: Elana Koren <ekoren@pivotallabs.com>