Implemented issue #93 - "Manually Specify Paths"

EECE310 L2A2 Group, implementing Issue #93

Crawljax is now able to crawl a path specified by using alsoCrawl() function in CrawljaxConfigurationBuilder. 

Short description regarding the implementation of this feature:
Instead of having one URL to store the seed URL, we replace the member variable with an ArrayList of URLs. By calling alsoCrawl(), new url specified by user will be added to this ArrayList.
WorkQueue is modified not to be final anymore, since it needs to crawl another URL once it is done crawling the seedURL.

Should there be any questions / concerns, please let us know.