Attempt at fixing unit test failures on TravisCI

Fixed toxi.ini so py.test is being called correctly when code coverage analysis is being done on this single-file project.

Also:
- Run code coverage on TravisCI for Python 3.4, 3.5, and 3.6
- Don't bother installing some modules which we aren't currently using for testing related to mocks
- Added detail to README regarding what the two different color libraries provide

Author: tleonhardt

README.md

@@ -33,8 +33,8 @@ Dependencies
 unicode strings rendered to a terminal.
 
 If you wish to use the optional support for color, then at least one of the following two modules must be installed:
-* [colorama](https://github.com/tartley/colorama)
-* [colored](https://github.com/dslackw/colored)
+* [colorama](https://github.com/tartley/colorama) - simple cross-platform colored terminal text with about 16 colors
+* [colored](https://github.com/dslackw/colored) - library for color in terminal with 256 colors, macOS and Linux only
 
 If both ``colorama`` and ``colored`` are installed, then ``colored`` will take precedence.
 

tox.ini

@@ -14,21 +14,21 @@ deps =
   codecov
   pytest
   pytest-cov
-  pytest-mock
 commands =
-  py.test {posargs} --cov
+  py.test {posargs} --cov=tableformatter
   codecov
 
 [testenv:py35]
 deps =
-  mock
+  codecov
   pytest
-  pytest-mock
-commands = py.test -v
+  pytest-cov
+commands =
+  py.test {posargs} --cov=tableformatter
+  codecov
 
 [testenv:py35-win]
 deps =
-  mock
   pytest
 commands = py.test -v
 
@@ -37,9 +37,8 @@ deps =
   codecov
   pytest
   pytest-cov
-  pytest-mock
 commands =
-  py.test {posargs} --cov
+  py.test {posargs} --cov=tableformatter
   codecov
 
 [testenv:py36-win]
@@ -48,12 +47,11 @@ deps =
   pytest
   pytest-cov
 commands =
-  py.test {posargs} --cov
+  py.test {posargs} --cov=tableformatter
   codecov
 
 [testenv:py37]
 deps =
   pytest
-  pytest-mock
 commands = py.test -v