Add protected appDidLaunch method for SDK wrappers

Refactor processApplicationBundle and reuse parts
Remove parameter logLevel from appDidLaunch method
Add special method sedSdkPrefix for SDK wrappers
Catch NullPointerException resulting from the recent extraction of PackageType
Merge pull request #26 from adeven/development

Support for SDK wrappers like Unity and Adobe Air
Update version to 2.1.3
Don't track first subsession in appDidLaunch
Handle NullPointerExceptions related to package persistence
Merge pull request #27 from adeven/development

Handle NullPointerExceptions related to package persistence
Update version to 2.1.4
RequestHandler: more generic exception catching to catch java.lang.AssertionError on executing the http request

AssertionError is thrown on some devices where for example MD5 is not available:
java.security.NoSuchAlgorithmException: MessageDigest MD5 implementation not found
Add documentation to support multiple broadcast receivers
Merge pull request #30 from adeven/development

Add documentation to support multiple broadcast receivers
Fix session interval
Fix event buffering
Fix default tracker
Fix environment
Update version to 2.1.5
Merge pull request #31 from adeven/development

Fix bugs introduced in recent refactorings
Add some TODOs to enable disabling of offline tracking