SV Now Supports PlaceHolderAPI 4.8.7 and up

As requested I have merged in a Place Holder API PR and finished fleshing it out. Below is the product:

sv-player-votes_{USERNAME} - returns the number of votes {USERNAME} has.
sv-top-name_{RANK} - returns the name of the person ranked Nth in top votes. {RANK} = int
sv-top-votes_{RANK} - returns the total votes of the person ranked Nth in top votes. {RANK} = int
sv-total-voters - returns the total number of active voters in the database.
sv-version - returns the version number of serious vote.