Implement semi-Bayesian block model inference

This includes code for expectation maximization with belief propagation
for the stochastic block model.
9 jobs for master
Status Name Job ID Coverage
  Test
passed job_clang_amd64 #1276
amd64

06:23:23

passed job_clang_amd64_nosh #1280
amd64

06:02:29

passed job_clang_py2_amd64 #1278
amd64

06:23:13

passed job_gcc_386 #1273
i386

09:13:02

passed job_gcc_amd64 #1275
amd64

05:31:48

passed job_gcc_amd64_nosh #1279
amd64

05:36:56

failed job_gcc_py2_386 #1281
i386

04:59:54

passed job_gcc_py2_amd64 #1277
amd64

05:13:18

failed job_gcc_py2_386 #1274
i386

07:19:16

 
Name Stage Failure
failed
job_gcc_py2_386 Test There is an unknown failure, please try again
Doctest summary
===============
828 tests
1 failure in tests
0 failures in setup code
0 failures in cleanup code
build finished with problems, 121 warnings.

ERROR: Build failed with: exit status 1