adds basic auth support and refactored MainHttpClient class.

fixes ushahidi#17

This handled adding user-agent and basic auth headers to all requests.
Allows easily adding query params or headers via `addParam`. and
`addHeader`.

Planning to reuse this class a bit more in some related callback
features. Also was planning to refactor MessageSyncHttpClient and use
the new methods to simplify a bit and show how to use the API.

I replaced the poorly named `getText` function with a `getResponse` and
`convertStreamToString` static method.

Also added `$` to URL_PATTERN in case you have that in your basic auth
password.
indentation/style tweaks.
added getParams, setEntity to MainHttpClient class.

also fixed bug with setting entity correctly.
refactored ProcessMessage and MessageSyncHtptClient classes.

Using new helpers in MainHttpClient.

added set/getClientError even though it's not being used yet, should
probably hook into wherever `getServerError` is called.
continued MessageSyncHttpClient refactor.

Changed constructor signature for MessageSyncHttpClient, added message
and phone. Updated tests.

Fixed call to `getFromWebService` in ProcessMessage, use MainHttpClient
instead.

Fixed bug in base class for request in MainHttpClient, use
HttpRequestBase instead of HttpUriRequest.

Removed executeGet/Post/Put, use setEntity, setMethod and executeRequest
separately.

Added `getRequest` to MainHttpClient for easier testing and backwards
compatibility.

Renamed `executeRequest` to `execute` to cover base class call.

Fixed bug in `String.format` calls.
removed `getFromWebService` method from MainHttpClient

added helper method `execute` that takes String method arg.
added basic auth test, bit more MainHTTPClient refactor.

Changed SyncSchemeTest tests to use try/catch since now
client.getRequest() will throw an exeption on encoding errors.

Removed `addHeader` using `setHeader` and HashMap.
removed stacktrace comment.
added example URL in howto on basic auth.
changed example urls to https.
changed example urls to https again.
Merge pull request #126 from mandric/http-client-refactor

adds basic auth support and refactored MainHttpClient class.