ENH: Avoid RuntimeWarning when hessian unused
TST: Remove unnecessary test.
Merge pull request #1543 from jseabold/tst-fix-warning

TST: Suppress RuntimeWarning for L-BFGS-B
CLN: Improve warnings to avoid generic warnings messages

All generic Warnings have been replaced with specific warnings, which have
been consolidated into sm_exceptions.py.

Conflicts:
	statsmodels/tools/sm_exceptions.py
Added specific warnings in a couple of places where they were missing

Converted raise Warning to warning.warn

Made certain warnings had been imported in some modules where it was lazily
imported

Simplified warnings in GEE which was neither lazily imported nor imported
at the top of the file
Fix for conda 3.4 changes
Merge pull request #1510 from bashtage/warning-convert

CLN: Improve warnings to avoid generic warnings messages
Merge pull request #1544 from bashtage/travis-miniconda

MAINT: Fix travis miniconda build
Merge pull request #1438 from toobaz/uncentered_table

ENH: Option to avoid "center" environment.
COMPAT: Add NumpyVersion from scipy
Merge pull request #1432 from jseabold/fix-loose-version

COMPAT: Add NumpyVersion from scipy
MAINT: Deprecate rank in favor of np.linalg.matrix_rank
COMPAT: Add np.linalg.matrix_rank for <= 1.7.1
ENH: Use NumpyVersion for version testing
Merge pull request #1383 from jseabold/deprecate-rank

MAINT: Deprecate rank in favor of np.linalg.matrix_rank
DOC: Fix link to wrong notebook [skip ci]
Merge pull request #1546 from jseabold/fix-example-links

DOC: Fix link to wrong notebook
MAINT: Fix missed usage of deprecated tools.rank
DOC: Add links for build machines. Closes #1153 [skip ci]
Merge pull request #1154 from jseabold/testing-machine-links

DOC: Add links for build machines.