- remove old miners
- replace xmr-stak-* with new, unified xmr-stak
- add xmrig

Increases privacy by requiring supported browsers to *not* send a
referer header. Also prevents tabnabbing.

Please review and comment

* removed whitespace added accidentally during rebase

* grammar:
    * a/an
    * repeated words
    * fragmented sentences
    * possesion
    * run on sentences
    * commas for prepositional phrases
    * is/are conjugations
    * was/were
    * its/it's
    * capitalizing proper nouns (Monero, Bitcoin, etc)
    * formatting (removed linefeeds in middle of sentences)
    * can not/cannot
    * removed commas improperly before conjunctions
* spelling:
    * programmatically
    * hashrate
    * transferring
    * scalability
    * separate
    * transactions
    * additionally
    * particular
    * profitability
    * recommended
    * explicitly
    * separator
    * block
    * drawback
    * favorite
* spelling (br/us)
    * internationalization
    * specialized
    * analyze
    * centralized
    * decentalized
    * memorizing
    * synchronization
    * synchronized