Bump Security Patch Level to 2018-04-01

Implemented patches
===================
CVE-2017-13274	A-71360761	High		Change 211308
CVE-2017-13276	A-70637599	Critical	Change 211309
CVE-2017-13277	A-72165027	Critical	Change 211310
CVE-2017-13278	A-70546581	High		Change 211347
CVE-2017-13279	A-68399439	High		Change 211348
CVE-2017-13280	A-71361451	High		Change 211349
CVE-2017-13267	A-69479009	Critical	Change 211350
CVE-2017-13284	A-70808273	Critical	Change 211351
CVE-2017-13287	A-71714464	High		Change 211352
CVE-2017-13289	A-70398564	High		Change 211353
CVE-2017-13290	A-69384124	High		Change 211354
CVE-2017-13294	A-71814449 [1]	Moderate	Change 211364
CVE-2017-13294  A-71814449 [2]	Moderate	Change 211365
CVE-2017-13295	A-62537081	Moderate	Change 211368
CVE-2017-13296	A-70897454	High		Change 211355
CVE-2017-13297	A-71766721	High		Change 211357
CVE-2017-13298	A-72117051	High		Change 211358
CVE-2017-13299	A-70897394	High		Change 211356

Skipped patches
===============
CVE-2017-13285  A-69177126      High	Can't fork svox due to DMCA
					If not merged, the patcher is in
                                        the 'asb-2018.04-cm13' topic on Gerrit
                                        
CVE-2017-13300  A-71567394*     High	Not publicly available

Change-Id: I8f2f06b674b3eb63648765e272d0623c35c04d60