Updated SageMath version to 8.5.rc0

VERSION.txt

-SageMath version 8.5.beta6, Release Date: 2018-12-02
+SageMath version 8.5.rc0, Release Date: 2018-12-10

build/pkgs/configure/checksums.ini

 tarball=configure-VERSION.tar.gz
-sha1=6d925a584556f44cd69f6968c9ba2e1c79779982
-md5=4382102bfcd516b8750fa9ce651e328e
-cksum=3778250311
+sha1=5e0ccb7f73d531b6a51f0e98780f2a45ae0510c4
+md5=a833043ff0835bfc260d702c97254f8f
+cksum=1311578579

build/pkgs/configure/package-version.txt

-294
+295

src/bin/sage-version.sh

 # Sage version information for shell scripts
 # This file is auto-generated by the sage-update-version script, do not edit!
-SAGE_VERSION='8.5.beta6'
-SAGE_RELEASE_DATE='2018-12-02'
-SAGE_VERSION_BANNER='SageMath version 8.5.beta6, Release Date: 2018-12-02'
+SAGE_VERSION='8.5.rc0'
+SAGE_RELEASE_DATE='2018-12-10'
+SAGE_VERSION_BANNER='SageMath version 8.5.rc0, Release Date: 2018-12-10'

src/sage/version.py

 # Sage version information for Python scripts
 # This file is auto-generated by the sage-update-version script, do not edit!
-version = '8.5.beta6'
-date = '2018-12-02'
-banner = 'SageMath version 8.5.beta6, Release Date: 2018-12-02'
+version = '8.5.rc0'
+date = '2018-12-10'
+banner = 'SageMath version 8.5.rc0, Release Date: 2018-12-10'