Update README with github installation
Update README with github installation

mross-pivotal/node-gemfire,gemfire/node-gemfire,mross-pivotal/node-gemfire,gemfire/node-gemfire,mross-pivotal/node-gemfire,gemfire/node-gemfire,gemfire/node-gemfire,mross-pivotal/node-gemfire,gemfire/node-gemfire,mross-pivotal/node-gemfire,gemfire/node-gemfire,mross-pivotal/node-gemfire