Soy for Python CL #2. Design Doc: []

With some renewed interested, work is back underway for the Soy to Python compiler.

This CL implements the sanitization generator for Python, as well as runs it to pull an update to normalized URIs. The generator extends AbstractGenerateSoyEscapingDirectiveCode and implements Python syntax where needed.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81604798
Soy opensource: manually note equivalence for Friday's push.

MOE magic is supposed to record CL <-> commit equivalences in moe_db.json. However, quirks in the way the Soy codebase is generated (for example, the inclusion of generated Javadoc in the Git repo) confuses MOE and causes it to consider the codebases different.

Until we can make the open-source codebase look more like the internal one, we should record equivalences manually. Without equivalences, MOE magic starts from the beginning of time, which takes a long time.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81691942
Soy opensource: add README.

(More or less copied from devsite.)
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81831054
Soy opensource: add README.md to MOE codebase.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81890478