finishedSpec: update description texts
test: add abortSpec
-node: implement "abort"
-browser: add some code comments in "abort" implementation
downloadingSpec: add 'has "total" be equal to output length'
uploadingSpec: add 'has "total" be equal to input length'
uploadingSpec: add "input" to all httpinvoke options
-browser: pass the downloadingSpec: 'has "total" be equal to input length'
test: move basicSpec.'returns abort function' to abortSpec.'does not throw'
change API - implement "options" argument to possibly be a function, which is used as a "finished" option