Updated comments in IApplication, ApplicationResource, and
ApplicationResourceIntegrationTest. Resolves #8
Resolves issue #4

1)Added getEnvironmentVariablesList(), and getEnvironmentVariablesMap()
to IApplication interface and its implementation, ApplicationResource.

2)Refactored references to getEnvironmentVariables() to
getEnvironmentVariablesMap().

3)Refactored environmentVariableByName to environmentVariablesMap.

4)Refactored getEnvironmentVariables():Map<String,IEnvironmentVariable>
      to return List<IEnvironmentVariable>.

5)Refactored reference to getEnvironmentVariables(), to reference
      getEnvironmentVariablesMap() in ApplicationTestUtils

6)Refactored reference to getEnvironmentVariables(), to reference
      getEnvironmentVariablesMap() in ApplicationResourceTest

7)Refactored reference to getEnvironmentVariables(), to reference
      getEnvironmentVariablesMap() in ApplicationResourceIntegrationTest