Fixing issue 446: R.java for aar libraries doesn't generate in some cases
fixing 'no resources found' issue when build apklib

this issue appears when building apklib module in which resources
uses resources from dependent aar module
Support no api level
Fixing issue 446: R.java for aar libraries doesn't generate. step 2
removing unused executor from ApklibMojo
Merge pull request #291 from marchelo/removing-unused-executor

removing unused executor from ApklibMojo
Merge pull request #287 from marchelo/issue-446

Fixing issue 446: R.java for aar libraries doesn't generate in some cases
Merge pull request #289 from marchelo/apklib-aar-resource-issue

fixing 'no resources found' issue when build apklib
Merge pull request #290 from william-ferguson-au/support_no_api_level

Supports no api level