find_device() requires initialize()/terminate() to properly access returned values

Merge pull request #2 from martinholters/compat-0.3

Compatibility with Julia 0.3 (using Compat package).

Change example in README to match new playrec/readwrite API

Rename playrec() to readwrite() and add new playrec() shortcut commands for direct access without stream handling

Update README to reflect latest API changes

Add play(), record() and record!() functions for direct playback and recording without the need to open and close a stream manually

initialize() and terminate() are now automatically called by all high-level API functions whenever necessary

Experimental support for asynchronous realtime IO and processing

AudioIO.jl credits for the low-level interfaces

Move simultaneous playback and recording example into an own file

PortAudio device index is now a standard julia integer in the public API

Add first basic tests, mainly interleaving/deinterleaving

Fix internal get_portaudio_devices() calls to match new API

Create own functions PortAudio.initialize() and PortAudio.terminate() to better follow the Julia naming scheme.