Smart change detection logic for compound attribute values

[fgalan]

checkAndUpdate() function includes the following comment:

// FIXME P6: in the case of compound value, it's more difficult to know if an attribute
// has really changed its value (many levels have to be traversed). Until we can develop th
// matching logic, we consider actualUpdate always true.

This issue is about solving this (some users has asked about this at SOF: http://stackoverflow.com/questions/26862953/contextbroker-vectors-update-with-unchanged-value-causes-onchange-subscription-n)

Effort: 4 man day

[fgalan]

Recently (after implementing #1068) is is not a just a matter of attribute compound values, but also metadata compound values. The logic in equalMetadataValue() is also affected.

See this PR comment for details: https://github.com/telefonicaid/fiware-orion/pull/2377/files#r71670648

[fgalan]

PR #4444

[fgalan]

Orion 3.11.0 is about to be released. Thus, we are closing this issue.