Remove tip4commit link

requested by lclc
Add links to install/build instructions
Add generic cmake instructions, remove android doc

Android build system is outdated
Merge pull request #177 from OttoAllmendinger/readme-build-instructions

Readme build instructions
Merge pull request #179 from yamamushi/develop

OTSignedFile FilePayload and SignerNymID
travis: install libzmq3-dev instead of libzmq3
Merge pull request #181 from toxeus/travisZmq

travis: install libzmq3-dev instead of libzmq3
OTSymmetricKey Decrypt unique_ptr release for user provided password pointer
Merge branch 'develop' of https://github.com/yamamushi/opentxs into develop