iam: fixes of fects found by UT:

iam: fixes of fects found by UT:

 - defect: iam_new_leaf(): fix typo in previous ext3_append() fix.

 - defect: iam_add_rec(): leaf node has to be added to transaction. 5 min.

 - defect: iam_lfix_split(): erroneously inserts physical block number instead of offset into parent node. 10 min.

 - defect: mark index node as dirty, when inserting new entry into it.

 - defect: LDISKFS_INDEX_FL flag cleared in iam_release_file() is not written to disk.

 - defect: iam_lfix_lookup(): wrong key comparison.

 - defect: iam_add_rec(): @leaf variable has to be refreshed as split may retarget path to the new leaf node.

 - defect: iam_lfix_lookup(): wrong return code (this made it impossible to remove last record in a node). 90 min.

iam-ut:

 - new IAM_IOC_DELETE ioctl command,

 - new functionality for lustre/tests/iam_ut