Arrange .gitignore files.

Delete Mercurial files not used.
Update rebar binary to a recent version.
Move type definitions to the .hrl file in include.
Modify Makefile to support build-plt and dialyze.

Also changed .gitignore to ignore *.plt
Fix type error found by dialyzer in lhttpc_client.erl.
Change dialyze and rel to dialyzer and release in Makefile.
Merge pull request #24 from Lastres/minor_changes

Minor changes