ACCUMULO-1471: more doc on SortedMapIterator explaining what you want if you're just looking for a simple Map-backed Iterator

Signed-off-by: John Vines <jvines@gmail.com>
Merge branch '1.5.1-SNAPSHOT'
ACCUMULO-1309 deprecated unused addSource method
ACCUMULO-1598 Fixes RFlile unit tests

The RFile tests had several tests in the @Ignore state.  Many
of these were redundant, so I simply excise them.  There were
a couple of missing files from the repository that the tests
needed; this patch adds them.

Signed-off-by: John Vines <jvines@gmail.com>
ACCUMULO-1614 added conditional writer randomwalk test