Update README.md

removing DO NOT USE because, we are using it :P
Specify minSdk in AndroidManifest

prevents complaints about calls not available in SDK version 1.
README.md: reference project issue tracker

also added some nice line wrapping
New IOCipherMountHelper class

Assists in opening IOCipher VFS mounts with CacheWord.
instant locking support

A timeout value of 0 triggers a lock event immediately.
handle disconnections properly

checkCacheWordState() should never be called when cache word is disconnected
Fix SecureRandom vulnerability

http://android-developers.blogspot.com/2013/08/some-securerandom-thoughts.html
fix service connection race condition resulting in ghost subscribers

If a connect and disconnect are received before the connection has
time to complete, the connection would complete AFTER it should have
already disconnected. The result was that CacheWordService never received
the detachSubscriber call, so the mSubscriberCount became inaccurate.
the persistent unlocked notification can now be disabled
Record version byte to facilitate future upgrades.

This will break all existing deployments of CacheWord. Thankfully
there aren't any yet.
Properly read the version byte from the byte array
Make the PRNG fixes optional
track bind state to the CW service

This prevents crashes when we call unbind but aren't actually binded, the crashes look like:

     java.lang.IllegalArgumentException:
     Service not registered: info.guardianproject.cacheword.CacheWordHandler