Resolves issue #4

 1)Added getEnvironmentVariablesList(), and getEnvironmentVariablesMap()
    to IApplication interface and 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
 
 8)Refactored ApplicationResource.environmentVariablesByName to 
	ApplicationResource.environmentVariablesMap