Upgrade nextcloud server package from 15.0.0 to 15.0.2 for Debian Stretch.

I highly recommend upgrading, check list of changes.

Process of upgrade is very simple, example:

apt-get update
apt-get upgrade

Changes (source from https://nextcloud.com/changelog/):

Version 15.0.2 January 11 2019

• Don't log parameters on user creation in case of error/exception (server#13479)
• RemoveClassifiedEventActivity: check if calendar still exists (server#13506)
• Broker: add timezone to CANCEL messages (3rdparty#196)

Version 15.0.1 January 10 2019

• Change doc link for 15 (server#12963)
• Use strengthify.min on personal settings page (server#12984)
• Use default cursor for disabled primary buttons (server#13007)
• Better activities for systemtags that are removed by CLI (server#13029)
• Ie11 compatibility updatenotifications (server#13076)
• Fix exception on LDAP mapping during login (server#13119)
• Fix SAML Client login flow on Apple devices (server#13123)
• Only trust the X-FORWARDED-HOST header for trusted proxies (server#13150)
• Prevent special characters from breaking the file drop remote url (server#13151)
• Allow content provider to generate new Index (server#13155)
• Make the footer "Get your own free account" translatable (server#13169)
• Use a case insensitive search for email (server#13179)
• Fix ie11 checkboxes (server#13206)
• SCSS cache buster is a combination of apps/theming/scc_vars (server#13209)
• Files list not rendering if user has favorites navigation unfolded (server#13215)
• Do not forgot to store the second displayname portion (server#13218)
• Add default values when parsing account data (server#13252)
• Fix opening search results for comments (server#13253)
• Fetch lastInsertId only when id null (server#13278)
• Add caching headers for public previews (server#13328)
• Unbundle user_external to release it via appstore (server#13329)
• Rewrite getNumberOfUnreadCommentsForFolder query (server#13335)
• Fix can change password check in case of encryption is enabled (server#13349)
• Update the CRL (server#13352)
• Check anonymous OPTIONS requests file in root (not in subdir) (server#13354)
• Re add the uploaded file list to file drops (server#13355)
• Returns a 404 instead of exception if app is not installed - #13088 (server#13357)
• Transpile arrow function for ie11 compatibility (server#13360)
• IE fix for apps menu (server#13361)
• Allow URI as data for vcard PHOTO (server#13366)
• Throttle with correct metadata (server#13368)
• Fix loginflow with apptoken enter on iOS (server#13370)
• Register and show when an LDAP user was detected as unavailable/deleted (server#13372)
• Fix apps menu overlapping (server#13404)
• Use the real logger in the settings (server#13405)
• CSP: Allow fonts to be provided in data (server#13411)
• HttpClient getHeader can return empty string (server#13425)
• Respect classification of calendar events in activity stream (server#13439)
• Add support for boolean default (server#13444)
• Show the repair steps and repair info output in the web for better feedback (server#13469)
• Fix PDF sidebar shown in PDF thumbnails (files_pdfviewer#114)
• Do not get the url from the download links (files_videoplayer#74)
• Use proper slogan from theming app (firstrunwizard#94)
• Update info.xml (firstrunwizard#96)
• Update richObjectStringParser.js (notifications#245)