Unknown duration error

[colinmcardell]

Fix for error when attempting to playback live audio streams.

A live stream will not return a duration or a current time value. Resolved issue #40 by checking player duration or currentTime against CMTIME_IS_INDEFINITE or CMTIME_IS_INVALID respectively and return -1 if invalid.

Adds methods to ReactPlayer for duration and position that accommodates check of live streams that wouldn't have a known duration or position. If duration and position are unknown/invalid the -duration or -position method will return -1. Implements usage of these methods in AudioPlayer allowing playback of live streams without throwing an error on the React side like RCTJSONStringify() encountered the following error: Invalid number value (NaN)... as the number now return will be -1.

This fix will cause no significant changes in usage of the library. Note again that live stream duration and position values will be -1.