__init__ can get default params from env vars

[msabramo]

• TEAMCITY_USER
• TEAMCITY_PASSWORD
• TEAMCITY_HOST
• TEAMCITY_PORT

$ python sample.py
{
    "userGroups": {
        "href": "/httpAuth/app/rest/userGroups"
    },
    "vcsRoots": {
        "href": "/httpAuth/app/rest/vcs-roots"
    },
    "version": "9.0.2 (build 32195)",
    "internalId": "7a775607-5420-4a17-86a1-543d755d7210",
    "currentTime": "20150224T141500-0800",
    "agentPools": {
        "href": "/httpAuth/app/rest/agentPools"
    },
    "versionMajor": 9,
    "buildNumber": "32195",
    "versionMinor": 0,
    "agents": {
        "href": "/httpAuth/app/rest/agents"
    },
    "startTime": "20150223T105439-0800",
    "builds": {
        "href": "/httpAuth/app/rest/builds"
    },
    "users": {
        "href": "/httpAuth/app/rest/users"
    },
    "buildQueue": {
        "href": "/httpAuth/app/rest/buildQueue"
    },
    "projects": {
        "href": "/httpAuth/app/rest/projects"
    },
    "buildDate": "20150130T000000-0800"
}

[msabramo]

Just updated README.md to document this enhancement:

https://github.com/msabramo/teamcity-python-rest-client/blob/init_default_env_vars/README.md

[msabramo]

This is very handy to keep private passwords from accidentally getting committed with code.