Convert README.md to README.rst

Break the content out into a number of smaller files. This makes
it easier to adopt to sphinx docs.
Include content from README in index.rst

remove the old temporary api file.
add dependency events

This should enable nicely decoupled monitoring/management solutions, able to trace dependencies.
fixes to the task register to support multiple tasks with the same name

This is needed in some cases where you have task wrappers and you wanted the wrapped task to be exposed over cmd line
Merge pull request #305 from erikbern/task-register

fixes to the task register to support multiple tasks with the same name
Merge pull request #301 from jcrobak/readme-md-rst-sphinx

Convert README.md to ReST and divide into several pages for sphinx
Added deep links to the example workflow and API overview

These were a little tricky to find with the new documentation
Merge pull request #310 from erikbern/doc-deeplinks

Added deep links to the example workflow and API overview
added a task to create a manifest file for redshift copy tasks
Merge pull request #312 from mortardata/cngan_add_redshift_manifest_task

added a task to create a manifest file for redshift copy tasks
Merge pull request #306 from spotify/ulzha/dependency-events

add dependency events
fix File.copy failure across filesystems

os.rename doesn't work across different filesystems.
conditionally skip redshift_test.py for lack of s3 stuff
Merge pull request #313 from spotify/ulzha/bugfixes

fix build problems/bugs:
Make --lock default to True. Add --nolock to provide lockless functionality when needed
Make nolock default when using luigi.build
Add String column types in the history db a length - as required by mysql dialect
Minor refactoring of Worker to allow easier subclassing
Merge pull request #319 from rantav/history_db_mysql_fixes

MySQL fixes to the history db
Renames flag to --no-lock and adds warning when --lock is used