Merge pull request #179 from Cxquan/0.4.0.0

change default value of AFR for normal work to 200000 (in millionth), which means normal work can tolerate 20% failure rate by default.
token based authentication caching
updated user guide document for advanced config UI enhancement
Merge pull request #180 from giteshnandre/advanced-config-UI-documentation

updated user guide document for advanced config UI enhancement
add null checking when disposing http client
add null check when disposing worker context
Merge branch '0.4.0.0' of https://github.com/intel-cloud/cosbench into 0.4.0.0
add log message when ping is failed.
add synchronization at closing http client to avoid race condition
move the flag for finished to watchdog
add flag for finished
fix a typo
enhance the logic for task termination
share one method in one client
Merge branch 'auth-token-cache' of https://github.com/giteshnandre/cosbench into giteshnandre-auth-token-cache
Merge branch 'giteshnandre-auth-token-cache' into 0.4.0.0
abort http connection before connection manager shut down
Revert "fix a typo"

This reverts commit 68c3943ff14390e9660d214dfb9a8cf42b925e5e.
Merge branch '0.4.0.0' of https://github.com/intel-cloud/cosbench into 0.4.0.0
Revert "share one method in one client"

This reverts commit 2a24a470228e7c28d763212cbc326d0f0b93bdd3.