remove sphinxcontrib-seqdiag

This removes the one seqdiag that is in our docs which drops the whole
chain of sphinxcontrib-seqdiag which requires Pillow, which requires
that you have a C compiler and jpeg-dev package on your environment to
build documenation for a python project.

Change-Id: Ie7615d48b5524b5e5e1159a25c357f5b3f0eee0e

doc/source/conf.py

@@ -33,7 +33,6 @@ extensions = ['sphinx.ext.autodoc',
               'sphinx.ext.graphviz',
               'oslosphinx',
               "ext.support_matrix",
-              'sphinxcontrib.seqdiag',
               'oslo_config.sphinxconfiggen',
               ]
 

doc/source/vmstates.rst

@@ -137,7 +137,15 @@ The following diagram shows the sequence of VM states, task states, and
 power states when a new VM instance is created.
 
 
-.. seqdiag::
+.. this is commented out because in order to turn this into a picture,
+   we need a rather large chain of python dependencies which includes
+   natively compiling against libjpeg. That's a huge cost for 1
+   diagram that's not clearly useful in that way.
+
+   I suggest we redo this as SVG or something to get the information
+   without the dependency change.
+
+   .. seqdiag::
 
        seqdiag {
          edge_length = 250;

test-requirements.txt

@@ -14,10 +14,6 @@ python-ironicclient>=0.8.0
 python-subunit>=0.0.18
 requests-mock>=0.6.0 # Apache-2.0
 sphinx!=1.2.0,!=1.3b1,<1.3,>=1.1.2
-# NOTE(tonyb): Pillow isn't used directly by nova but it's needed for
-# sphinxcontrib-seqdiag.  Make sure we honnor g-r caps
-Pillow<3.0.0,>=2.4.0 # MIT
-sphinxcontrib-seqdiag
 oslosphinx>=2.5.0 # Apache-2.0
 oslotest>=1.10.0 # Apache-2.0
 os-testr>=0.4.1