release candidate v0.1

This version of ssh_job will be tested on different resources, and should then
be released.  This completes the list of known limitations, and fixes some
smaller problems.

Below are some (still preliminary) performance numbers::

  merzky@thinkie:~/saga/saga-python (feature/sshjob *$%) $ python
  tests/_andre/test_perf.py

  n_services n_jobs   time jobs/sec memory  targets
          10   1000   4.59   217.92  22196  10*fork://localhost/
          10   1000   5.41   184.90  23544  10*fork://localhost/
          10   1000   6.55   152.56  24960  10*fork://localhost/
          10   1000   5.09   196.65  25384  10*ssh://localhost/
          10   1000   5.37   186.06  26028  10*ssh://localhost/
          10   1000   5.39   185.44  26388  10*ssh://localhost/
          10   1000  28.40    35.21  24668  10*ssh://amerzky@cyder.cct.lsu.edu/
          10   1000  29.70    33.67  24732  10*ssh://amerzky@cyder.cct.lsu.edu/
          10   1000  30.37    32.93  24692  10*ssh://amerzky@cyder.cct.lsu.edu/
          10   1000  30.20    33.11  24956  10*ssh://repex1.tacc.utexas.edu/
          10   1000  33.04    30.27  24800  10*ssh://repex1.tacc.utexas.edu/
          10   1000  34.65    28.86  24676  10*ssh://repex1.tacc.utexas.edu/
          10   1000  40.87    24.47  25960  10*gsissh://ranger.tacc.utexas.edu/
          10   1000  39.94    25.04  25680  10*gsissh://ranger.tacc.utexas.edu/
          10   1000  40.58    24.64  22580  10*gsissh://ranger.tacc.utexas.edu/