Mbed-flasher

This release contains breaking changes: flash and erase python API's raises now exception instead of returning boolean. This also add retry for DAPLink transient and user errors.

Changes
117 Refactor flash and erase error handling

Another fix for the flash verification. Wait for mbed.htm to appear to board mount point before progressing further.

All changes
Wait mbed.htm appear after flash (122)

Bring back binary disappear check after flash.
Fix for a test problem where CI would not always run hardware tests.

All changes
Separate folders for hw and non hw tests (120)
Refactor binary disappear wait (118)
update mbedls (116)

This release fixes some corner cases which could causes flash failure and update latest release [mbed-ls](https://github.com/ARMmbed/mbed-ls/releases/tag/v1.4.1).

Changes

114 Update mbed-ls to [1.4.1](https://github.com/ARMmbed/mbed-ls/releases/tag/v1.4.1)
113 Increase mbedls refresh retries to 100
112 Fix: stop CI build if pip install failed
111 Retry flashing on specific error conditions

This release brings support for using JLinkExe for JLink board flashing.
JLinkExe (or JLink.exe in Windows) is used over drag'n'drop method if the said program is found from path.

All changes
Delete JLink commander file separately (110)
Flash boards with JLink firmware using JlinkExe (108)

Update mbedls to version 1.4.0, which adds JLink board detection.

All changes
Update mbed-ls to v1.4.0 (106)
Hardcode binary instead of weird search (c330f2e579cc6a06bc71ac2ffb0559bb813fd731)