[Internals] Make generation easier to debug

[SentryMan]

Modifies the Append Class to have a toString implementation using stringbuilder. In this way, we can easily debug file formatting/generation issues in a debugger

[rbygrave]

For debugging I tend to generate comments into the source code. I'm kinda thinking that this potentially will add a decent amount of extra memory consumption/churn for everyone running the annotation processor [not just us]? Hmmm.

[SentryMan]

For debugging I tend to generate comments into the source code.

I like to debug the annotation processor with my eclipse while it's running using the InjectProcessorTest.

will add a decent amount of extra memory consumption

I'll make it a flag that's turned off by default then