Handle rebar dependencies better

Download dependencies specified in rebar.config and go through
Converger to handle conflicts.
Handle `sub_dirs` in rebar.config when getting dependencies and
by the sub_dirs to the code load path.
Handle raw option in rebar deps
Clean up code, add tests, fix bugs found in tests
Use Mix.Rebar as module for project pushing
Change project/rebar to manager/source in Mix.Dep
Use rebar from project root directory
Merge pull request #1122 from ericmj/mix-rebar

Handle rebar dependencies better
Better error message for Binary.Chars.List.to_binary. Closes #1144
Merge pull request #1150 from alco/to_binary-error

Better error message for Binary.Chars.List.to_binary. Closes #1144
document update and to_keywords
Mix.Shell: Fix incorrect Windows' COMSPEC handling
Minor indentation fix
Support extended syntax in Regex.escape
Improve Regex.escape tests
Add documentation to Regex.escape
Do not interpret ansi escape codes in IEx results
Merge pull request #1164 from sasa1977/document_record_features

documentation for record generated functions
Merge pull request #1163 from meh/regex-escape

Support extended syntax in Regex.escape
Update changelog and move version to 0.9.2.dev
Don't process ANSI escapes in strings in IEx