NXP-14603: Write multipart boundary in the Content-Type header
NXP-14603: Removed lower casing of the Content-Type header value.
Merge pull request #19 from nelsonsilva/NXP-14603

NXP-14603: Fix multipart handling
NXP-14645: fix incorrect labels
NXP-14613: make sure quotes are doubled in messages with parameters, and not doubled in messages without parameters
NXP-14644: queue request to server