[ENH][WIP]extension of #339: Rahul799 docs/bugfix

[jGaboardi]

This PR was initialized as #339 by @rahul799, which addresses #336 and #338. Also, this PR partially addresses #340 and #341.

[jGaboardi]

Failing due to a minute rounding error on different machine (this passed locally).

https://travis-ci.org/pysal/spaghetti/jobs/628544676#L863-L879

File "/home/travis/build/pysal/spaghetti/spaghetti/network.py", line 1557, in spaghetti.network.Network.allneighbordistances
Failed example:
    s2d_dist[0,0], s2d_dist[1,0]
Expected:
    (4520.72353741989, 6340.422971967316)
Got:
    (4520.72353741989, 6340.422971967315)

[coveralls]

Pull Request Test Coverage Report for Build 2059

• 184 of 185 (99.46%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.3%) to 96.675%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
spaghetti/network.py	75	76	98.68%

Totals
Change from base Build 2042:	0.3%
Covered Lines:	9376
Relevant Lines:	9597

---

💛 - Coveralls

[jGaboardi]

Current failures are non-blocking and due to #343 This appears to have been remedied.