use dropsonde for logging

[#74343664]

Signed-off-by: Johannes Petzold <jpetzold@pivotal.io>
remove loggregatorlib dependencies

[#74343664]

Signed-off-by: Johannes Petzold <jpetzold@pivotal.io>
merge from master

Signed-off-by: Andrew Poydence <apoydence@pivotal.io>
Merge remote-tracking branch 'origin/pr/56'