Lint fix: NewApi

Encryptor#init already has a version check, so we can safely wrap the
whole method as @TargetApi(HONEYCOMB)

OAuthWebviewHelper.BaseRinishAuthFlowTask#onPostExecute was using
String.isEmpty, which was added in API 9, but the library project is
currently set to build with API 8. This was replaced with a call to
TextUtils.isEmpty(CharSequence)
Lint: DefaultLocale

Replaced calls to String.toLowerCase() with
String.toLowerCase(Locale.US). Locale.US is guaranteed by Java to be
installed, and can be used to downcase URLs expressed as
Strings.
Lint: ContentDescription

The login header "reload" ImageView could use a contentDescription.
Merge pull request #439 from jasonschroeder/Lint-NewApi

Lint fix: NewApi
Merge pull request #441 from jasonschroeder/Lint-ContentDescription

Lint: ContentDescription
Merge pull request #440 from jasonschroeder/Lint-DefaultLocale

Lint: DefaultLocale
Test fix. SalesforceSDK-Android v2.1 has been released, bumping up
some test data to make all test case versions newer than v2.1.
Merge pull request #442 from jasonschroeder/testfix-JavaScriptPluginVersionTest

Test fix.
Update README.md

Fixed code block formatting in one of the steps.
Merge pull request #444 from rwhitley/master

Update README.md
Merge branch 'master' into unstable
Merge pull request #445 from bhariharan/unstable

Merge branch 'master' into unstable
Merge from unstable