Multilogit: NULL handling for regression and estimators

Pivotal Tracker: 57194990, 57195142

Additional author:
    Shengwen Yang <syang@gopivotal.com>

Changes:
    - Added NULL handling for Multinomial logit regression
    - Added NULL handling for robust/clustered/marginal estimators for
    Multinomial logit regression
    - Changed interface of mlogit to output a table instead of returning result
    type
    - Refactoring to improve code flow
Utilities: Fix issue with keyerror
Estimator methods: Replace verbose since it is keyword
Estimator methods: Change verbose name in python as well
NULL handling for estimators of Linear/Logistic regressions

Pivotal Tacker: 57195098 and 57195034

Gracefully handle the NULL values for Huber-White/Clustered/Marginal on
both linear and logistic regressions.
Estimators: PEP8 certification + remove verbose keyword

Changes:
    - Multiple small changes to remove PEP8 errors
    - Ensure that 'verbose' is replaced  'verbose_mode' due to possible keyword
    error in Postgresql
    - Re-added use of 'regr_coef' in marginal code to not call underlying
    multinomial regression if the coefficient is provided.
Turn off ORCA in lda.get_perplexity and simplify the query
Merged the reformat of multi-logistic regression and its estimators

Pivotal Tracker: 60428124 60053908

Each category now occupies a separate row. This better output format is
implemented for multilogit regression and Huber-White estimator,
clustered estimator, marginal effect.
Marginal Effects: Fix invalid key in python error
Multilogistic: Return error if all observations in category has missing data

Pivotal Tracker: 60643012

Changes:
    - For mlogit and all estimators for mlogit, we find the all categories
    in data and subtract from this set all categories with at least 1 non-missing
    data observation. If this set-difference is not empty, then an error is
    returned.
    - Also fixed a problem in Python AL for validation of arguments.
Bug fix: made margins and std_err consistent with Stata

Pivotal Tracker: 61087446 61005454

In mutltilogit and logit marginal effects, both margins and std_err are
evaluated as the averages of the quantities instead of evaluating at the
means. This behavior is consistent with the Stata default behavior of
the function "margins".
Postgres 9.3 Support

Contributor: Caleb Welton <Caleb.Welton@emc.com>

Pivotal Tracker: 55859820

- Added PostgreSQL 9.3 as a port that allows MADlib to build from source
- Fixed useless dump messages (JIRA: MADLIB-782)
Turn off ORCA for left outer join

Pivotal Tracker: 60643522

Additional author: Qian, Hai <hqian@gopivotal.com>

- Fixed kmeans failures due to left outer join
- Refactored kmeans to use the iteration controller in utilities module
Documentation: Add brief descriptions for all modules

Other authors:
    - Rahul Iyer <riyer@gopivotal.com>
    - Srivatsan Ramanujam <sramanujam@gopivotal.com>
    - Feng, Xixuan (Aaron) <xfeng@gopivotal.com>
Upgrade: Add script to upgrade to v1.4 from v1.0+

Pivotal Tracker: 58478266

Changes:
    - Added all changelist files to upgrade to v1.4 from v1.0, v1.1,
      v1.2 and v1.3
Logistic regression: Added the help message

Also updated the help messages for linear, estimators of regressions to
add the description of summary tables.
Bug fix: SVD works for flexible source tables

Pivotal Track: 61320838

Additional author: Feng, Xixuan (Aaron) <xfeng@gopivotal.com>

- Fixed a bug that only source table with fixed column names can work,
otherwise, an error is raised unexpectedly
- Install-check tests are revised to also test this fix
Documentation: Fix various inconsistencies in documentation

Pivotal Tracker: 58478260

Additional authors:
    - Hai Qian <hqian@gopivotal.com>
    - Shengwen Yang <syang@gopivotal.com>
    - Xixuan Feng <xfeng@gopivotal.com>

Changes:
    - Complete the Release notes
    - Gppkg version number set to 1.8
    - Fix various documentation errors in multiple modules
    - Changed incorrect function declaration in margins_mlogregr