Missing dependencies in Makefile.PL

[lelutin]

Hello,

This library uses some other libs as dependencies, as can be seen here:

https://github.com/raphaelthomas/InfluxDB-HTTP/blob/develop/lib/InfluxDB/HTTP.pm#L13-L16

however, they are not defined as dependencies in the Makefile.PL file.

This means that to use this lib one needs to add them in manually in upstream projects.

Note: #7 touches up on this by adding the missing dependencies, but it's also adding features and more dependencies.