Added multiple term search functionality (with default phrase search)

This pull-request is very similar to #5496
Change allows:
* in addition to the standard (phrase) search adds functionality to search multiple words separated by a space (multiple terms search)
* define the word (or word list) to search in the url hash tag #search. When page has been loaded, document is scrolling to the search results.
* specify the type of search (phrase or multiple term search) in the url hash tag #phrase (true or absent hash tag - default phrase search, false - multiple term search)
* specify the type of search (phrase or multiple term search) in UI (checkbox 'Phrase', by default this is checked).

![pdfjspull](https://cloud.githubusercontent.com/assets/10258064/5538374/73ff2626-8ad4-11e4-843e-870d821cf76c.png)

Examples:
find phrase 'Locking tames tamed tame':
#search=Locking%20tames%20tamed%20tame&phrase=true
or 
#search=Locking%20tames%20tamed%20tame

find multiple term search 'Locking tames tamed tame':
#search=Locking%20tames%20tamed%20tame&phrase=false

Screenshots:
![pdfjspull-phrase](https://cloud.githubusercontent.com/assets/10258064/5538444/051c58e4-8ad6-11e4-95a5-42c01f9fbd24.png)

![pdfjspull-multiple](https://cloud.githubusercontent.com/assets/10258064/5538446/0c22a3c8-8ad6-11e4-9e99-59ee68e4482c.png)


Nit: for readability, please use proper sentences in comments. I.e. always begin sentences with an upper case letter, and end it with a period.
This applies in a couple of other places as well, so please go through the comments you've added in this patch and update them if necessary.