patch_all() is unsafe

There is a bit of ambiguity of `patch_all()` approach on `aws-xray-sdk-python`. Use thereof automatically enables new patchers regardless to how well they've been tested against real use cases (https://github.com/aws/aws-xray-sdk-python/issues/48, https://github.com/aws/aws-xray-sdk-python/issues/90). This in turn can can lead to a nasty surprise where deployment of lambda function will not work as it patches the calls.

Some ideas on making the situation better:
1. Discourage use of `patch_all()`due to its unsafe nature.
2. Do not include new patchers in `patch_all()` outside of major versions
3. Split `patch_all()` into two functions `patch_all()` and `patch_all_bleeding_edge()` where new, and un-vetted patchers are first introduced into `patch_all_bleeding_edge()` and after they've been tested are then introduced to `patch_all()`

Inizia individuando l’implementazione dell’SDK Python e i chiamanti di patch_all(), poi leggi le issue collegate #48 e #90 e verifica il fallimento del deployment Lambda descritto qui. Per considerarlo completato è necessaria una policy selezionata da un maintainer per i nuovi patcher e una modifica concordata all’API o al comportamento; questa issue non indica file né test.

Scritto dal modello di indicizzazione a partire dal testo della issue.