v0.6.7

Bug fixes and minor improvements:

• Added http_custom_web config option to serve user-defined files
• Added trim_interval config option to modify the database trimming interval
• Addes support for more handler fields: desc, gpsalt, gpspos
• Downlink handlers can now return a list to trigger multiple messages

This is the last release that supports Erlang/OTP 19.2.
Please note that SMTP functions in this (and all previous releases) will not work with Erlang 22 due to gen-smtp/gen_smtp#168.