write dts to the timestamp part of the flv header, not pts

The Flash decoder expects the FLV timestamp to be the decoding timestamp not the
presentation timestamp. Using pts creates noticable bugs when using a
non-baseline H264 profile.
update documentation for the getMediaIndexByTime routine
documentation normalization
Merge pull request #121 from videojs/hotfix/documentation

update documentation for the getMediaIndexByTime routine
Merge pull request #106 from gutworth/ts-dts

write dts to the timestamp part of the flv header, not pts