Feature/local flow

[memsharded]

Hello!

These changes enable the local workflow with the Poco project.
I based the changes on master, not sure about the base branch if master or release/1.9.0.

In short, the package can be fully created, debugged and tested locally (in user folders):

$ pip install conan --upgrade # MUST do to 1.2.0, it is necessary
$ git clone http://github.com/pocoproject/conan-poco
$ cd conan-poco
$ conan source . -sf=tmp/src
$ conan install . -if=tmp/build
$ conan build . -sf=tmp/src -bf=tmp/build
$ conan package . -sf=tmp/src -bf=tmp/build -pf=tmp/pkg
# conan package is optional, can directly do export-pkg
$ conan export-pkg . user/testing -sf=tmp/src -bf=tmp/build -f
$ conan test test_package Poco/1.9.0@user/testing
# And then, the full cache flow should work too
$ conan create . user/testing

More info about the local flow: http://docs.conan.io/en/latest/creating_packages/package_dev_flow.html

Cheers.