Add changes to the registration process for DEET

[prathamesh920]

1. OTP reduced to 6 chars and only numeric.
2. OTP sent everytime when registration is done by same user for different foss.
3. callbackurl saved
4. Status is sent via callbackurl whenever it is updated
5. Removed password field

[pep8speaks]

Hello @prathamesh920! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file cms/views.py:

Line 70:1: E302 expected 2 blank lines, found 1
Line 71:11: E271 multiple spaces after keyword

• In the file donate/views.py:

Line 14:48: E231 missing whitespace after ','
Line 201:20: E126 continuation line over-indented for hanging indent
Line 203:27: E231 missing whitespace after ':'

• In the file events/viewsv2.py:

Line 2939:3: E111 indentation is not a multiple of four
Line 2940:6: E111 indentation is not a multiple of four
Line 2941:6: E111 indentation is not a multiple of four
Line 2942:6: E111 indentation is not a multiple of four
Line 2943:16: E126 continuation line over-indented for hanging indent
Line 2945:23: E231 missing whitespace after ':'
Line 2950:6: E111 indentation is not a multiple of four
Line 2951:1: W293 blank line contains whitespace
Line 3581:7: E111 indentation is not a multiple of four

• In the file training/views.py:

Line 147:1: W191 indentation contains tabs
Line 150:1: W191 indentation contains tabs
Line 153:1: W191 indentation contains tabs
Line 195:1: W191 indentation contains tabs
Line 206:1: W191 indentation contains tabs
Line 210:1: W191 indentation contains tabs
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Line 212:1: W191 indentation contains tabs
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Line 215:1: W191 indentation contains tabs
Line 216:1: W191 indentation contains tabs
Line 217:1: W191 indentation contains tabs
Line 218:1: W191 indentation contains tabs
Line 219:1: W191 indentation contains tabs
Line 220:1: W191 indentation contains tabs
Line 221:1: W191 indentation contains tabs
Line 222:1: W191 indentation contains tabs
Line 223:1: W191 indentation contains tabs
Line 224:1: W191 indentation contains tabs
Line 225:1: W191 indentation contains tabs
Line 226:1: W191 indentation contains tabs
Line 227:1: W191 indentation contains tabs
Line 243:1: W191 indentation contains tabs
Line 273:1: W191 indentation contains tabs
Line 317:1: W191 indentation contains tabs
Line 318:1: W191 indentation contains tabs
Line 319:1: W191 indentation contains tabs
Line 320:1: W191 indentation contains tabs
Line 321:1: W191 indentation contains tabs
Line 321:14: E231 missing whitespace after ':'
Line 322:1: W191 indentation contains tabs
Line 323:1: W191 indentation contains tabs
Line 324:1: W191 indentation contains tabs
Line 325:1: W191 indentation contains tabs
Line 326:1: W191 indentation contains tabs