Fix sslVerify default=true for grafanaNet route using new syntax

[Dieterbe]

Master:

config	sslVerify property
unspecified	false
true	true
false	false

When the value is not specified it should default to true.
Our code doesn't know the difference between unspecified and explicitly specified to false,
so it assumes the latter, and when unspecified, changes the value from the default (true) back to false.

With patch applied:

config	sslVerify property
unspecified	true
true	true
false	false

Notes:

• this affects all boolean config options that default to true. but sslVerify is the only case of this.
• the deprecated old syntax does not have this problem
• SslVerify, SSlVerIfy, SSLVERIFY all work to set the value explicitly (with new syntax)
• This issue came up briefly at Unmarshal with default values BurntSushi/toml#47
  It's unfortunate to have to patch the toml dependency code, I tried doing it more cleaner using
  something like meta.IsDefined("route", "sslverify") but couldn't get that to work
  as we have a slice of routes, and the IsDefined doesn't seem to support iterating over a slice and finding
  a specific route.

[woodsaj]

lgtm

would have been nicer if we just originally named the arg sslSkipVerify or similar so we could have a default value of False. But changing the arg name now would be a pain.