add automake and autoconf to dependencies

If the system have not been installed the automake tools,
command"aclocal,automake,autoreconf" can not be recognized，
so add it to readme.md to make the readme file more clearly.

Signed-off-by: zhoumeina <zhoumein@linux.vnet.ibm.com>
Add ignore_missing parameter to ObjectStoreSession.delete() method

It makes delete() method more flexible.
It is useful while removing virtual machines as only the virtual machines
created through kimchi UI are stored in the local database.
To avoiding errors while trying to remove a virtual machine created through
another method (ex. virt-manager), turn ignore_missing parameter true.

Signed-off-by: Aline Manera <alinefm@br.ibm.com>