More detailed and specific machine info detection in TKG

[renfeiw]

TKG checks machine info through MachineInfo.java. At the current stage, not all machine info commands are tailored based on platforms. We would like to improve this by identifying which commands work on which platform and conditionally use different commands on different platforms. An example is

TKG/src/org/openj9/envInfo/MachineInfo.java

Line 175 in 5d83f85

if (System.getProperty("os.name").toLowerCase().contains("mac")) {

[smlambert]

related: #45