noted that java 8 can also be used, added links to Oracle jdk install guides
noted that java 8 can also be used, added links to Oracle jdk install guides

fimkrypto/nxt,fimkrypto/nxt,fimkrypto/nxt,fimkrypto/nxt,Ziftr/nxt,Ziftr/nxt,Ziftr/nxt